[Pladi]

Originally Posted by fatty335

Very, very little difference between these oil grades when at operating temp. I would be extremely surprised if Xw30 vs. Xw40 is in any way causal to these failures. Old oil, low oil, fuel or meth or coolant diluted oil, or some form of oil starvation are much more likely culprits.

the very little difference when you are looking at 0.001 tolerances might make a difference.. we dont know.. there are alot of speculations nothing concrete. Personally all i am saying is no reason anyone should be using 40 weight anyways.. You speculate and i speculate.. thats all we have seen

To add when at 20 degrees Celsius the oils are quite different for someone that does short trips it might make a difference.. again we dont know.

[fatty335]

Originally Posted by Pladi

the very little difference when you are looking at 0.001 tolerances might make a difference.. we dont know.. there are alot of speculations nothing concrete. Personally all i am saying is no reason anyone should be using 40 weight anyways.. You speculate and i speculate.. thats all we have seen

To add when at 20 degrees Celsius the oils are quite different for someone that does short trips it might make a difference.. again we dont know.

Perhaps you are correct, Pladi. I run Belgium Castrol 0W40 in both of my n55 equipped vehicles (readily available at local chain stores, is LL 01 & A3/B4 approved). From the research I have done, GC or BC 0w30, 5w30, and 0w40 are all LL 01 & A3/B4 approved, and are all within a gnats rear end where viscosities at various temps are concerned. This post http://www.bobistheoilguy.com/forums...pics/3535964/1 on BITOG offers great discourse on the differences between BC 0w30 & 0w40. To my surprise, it also includes the following: "the 0w-40 becomes thinner than the 0w-30 @ -5c or 23f, though there's not a significant difference until you get below -25c or -13f, where the 40w is much thinner."

I have to believe that the engineers at BMW knew what the tolerances of the n55 bearings were in 2010 and spec'd the recommended grades of anywhere between 0w30 and 5w40 accordingly. I just don't think the oil's viscosity is causal here.

[Pladi]

Originally Posted by fatty335

Perhaps you are correct, Pladi. I run Belgium Castrol 0W40 in both of my n55 equipped vehicles (readily available at local chain stores, is LL 01 & A3/B4 approved). From the research I have done, GC or BC 0w30, 5w30, and 0w40 are all LL 01 & A3/B4 approved, and are all within a gnats rear end where viscosities at various temps are concerned. This post http://www.bobistheoilguy.com/forums...pics/3535964/1 on BITOG offers great discourse on the differences between BC 0w30 & 0w40. To my surprise, it also includes the following: "the 0w-40 becomes thinner than the 0w-30 @ -5c or 23f, though there's not a significant difference until you get below -25c or -13f, where the 40w is much thinner."

I have to believe that the engineers at BMW knew what the tolerances of the n55 bearings were in 2010 and spec'd the recommended grades of anywhere between 0w30 and 5w40 accordingly. I just don't think the oil's viscosity is causal here.

In any type of troubleshooting you have to be very open minded and consider all options. Only then you will find a root cause. I am sure the BMW engineers know what they are doing but mistakes are made and the recent sudden switch to lower weight officially by BMW is interesting to say the least. For that reason i will continue to use 5W-30. Its def turning into an oil debate and thats ofcourse not my intention. We want to see as much data as possible to reach any kind of conclusions.

[bbnks2]

I don't think 15 people with 0 automotive engineering expertise on a forum are going to find some technical flaw in the motor or BMW's recommendation.

My own personal theory is that this is a very tight tolerance motor with very high oil volume/flow requirements. The oil spec'd is perfectly fine for 99% of the consumer market. Put the car into a performance situation though and now consider what happens when topping out 4th or 5th gear and/or doing some high g-force turns...

Extended time at high revs = high volumes of oil flow and thick oil = oil that doesn't drain back to the pan very well. Thinner oil like a 20-30wt would help with this situation (if my theory is accurate). Oil flow protects bearings not pressure. Thicker oil produces nice high oil pressure, but at high rpms it means less FLOW due to pumping losses of the thicker fluid. Thinner oil would flow better at high rpm but might also require driving the oil pump harder to produce the same PRESSURE. I believe these cars do have some overhead in that area... we run a fairly beefy oil pump. The oil would be able to drain back to the pan faster and bearings with tight tolerances would be better protected with adequate FLOW to maintain the oil wedge.

Again, we need an actual engineer to weigh in because I could be way off base with these comments. Preferably one that has some experience tearing down these motors. I think I read somewhere by ABR or MMP or someone who has a rebuild program that side-play allows oil to escape the bearing race too easily? That changes the scenario entirely. I have never measured these clearances. I base my comments on seeing BMW shooting for a rod bearing clearance of .00135" (with an allowable threshold of between .0007" and .002") and also BMW switching their allowed oils for "M" motors to 5-30wt. They surely aren't recommending anyone run thicker oils... A high quality 30wt oil can provide the same film strength and shear resistance as a 40wt oil. Castrol edge is a perfect example. Both their LL-01 "European formula" 0-30 and 0-40 oils have the same HTHS rating of 3.5cp. The 0-30wt will just flow a bit better through the motor.

I have my motor torn down right now. I spun a rod bearing on track. Looks like oil starvation locked the motor up almost instantly. But, looking at the oil pan, I can't see how it could've been from oil sloshing OUT of the oil pickup area. It is very deep with vertical walls. Once the oil is down there it is not sloshing out. The pickup is even slanted so that in hard Left hand turns the pickup tube is still going to be flat with the plane of oil level. An exception to this MIGHT BE hard RIGHT HAND TURNS. A right hand turn would cause oil to slosh the opposite direction of the slanted cut of the oil pickup tube. If even the slightest edge of the tube becomes uncovered you suck up air. Again, the pan should be pretty damn full if you run 1/2qt overfilled... Even the M2 uses the same pan and a slightly modified pickup tube. No special baffles or anything.

The only other explanation to me is that oil didn't drain back to the pan fast enough. Or, oil doesn't drain down into the rear of the pan, where the pickup is, under high g-forces and a forward pitch of the motor. There is not much you can do about that. Some cars (even BMWs) run a dual pickup tube that will pull oil from both the front and the rear of the oil pan to prevent this type of issue... That is hardly something that should be necessary for 99% of people and an Accusump would be cheaper and easier insurance.

So, if it's not an oil weight thing then what else could it be. Maybe rod bolt stretch? Heat caused metal to expand (not likely as temps were not bad)? Foreign objects like dirt? Nope my motor was damn clean inside... Maybe a failed OFHG? VERY POSSIBLE as I just changed the OFHG but I also saw no sings of coolant in the oil but maybe with how hot the oil was on track it was burning right off? Fuel Dilution? Not likely on an N55 and no other signs present. I have never seen the AFR "hang" in off-throttle situations either.

I drained out 7qts of oil. It was full. No metal anywhere except in the oil filter but damn my bearings were burnt and welded to the crank. I'll be putting in an ACCUSUMP for the rebuild because this looks to me like a case of sudden loss of oiling for whatever reason... DME shows no codes of oil pressure loss. Unfortunately, I was using the OBD to get video data when it happened and not MHD logging data.

[Pladi]

Originally Posted by bbnks2

I don't think 15 people with 0 automotive engineering expertise on a forum are going to find some technical flaw in the motor or BMW's recommendation.

My own personal theory is that this is a very tight tolerance motor with very high oil volume/flow requirements. The oil spec'd is perfectly fine for 99% of the consumer market. Put the car into a performance situation though and now consider what happens when topping out 4th or 5th gear and/or doing some high g-force turns...

Extended time at high revs = high volumes of oil flow and thick oil = oil that doesn't drain back to the pan very well. Thinner oil like a 20-30wt would help with this situation (if my theory is accurate). Oil flow protects bearings not pressure. Thicker oil produces nice high oil pressure, but at high rpms it means less FLOW due to pumping losses of the thicker fluid. Thinner oil would flow better at high rpm but might also require driving the oil pump harder to produce the same PRESSURE. I believe these cars do have some overhead in that area... we run a fairly beefy oil pump. The oil would be able to drain back to the pan faster and bearings with tight tolerances would be better protected with adequate FLOW to maintain the oil wedge.

Again, we need an actual engineer to weigh in because I could be way off base with these comments. Preferably one that has some experience tearing down these motors. I think I read somewhere by ABR or MMP or someone who has a rebuild program that side-play allows oil to escape the bearing race too easily? That changes the scenario entirely. I have never measured these clearances. I base my comments on seeing BMW shooting for a rod bearing clearance of .00135" (with an allowable threshold of between .0007" and .002") and also BMW switching their allowed oils for "M" motors to 5-30wt. They surely aren't recommending anyone run thicker oils... A high quality 30wt oil can provide the same film strength and shear resistance as a 40wt oil. Castrol edge is a perfect example. Both their LL-01 "European formula" 0-30 and 0-40 oils have the same HTHS rating of 3.5cp. The 0-30wt will just flow a bit better through the motor.

I have my motor torn down right now. I spun a rod bearing on track. Looks like oil starvation locked the motor up almost instantly. But, looking at the oil pan, I can't see how it could've been from oil sloshing OUT of the oil pickup area. It is very deep with vertical walls. Once the oil is down there it is not sloshing out. The pickup is even slanted so that in hard Left hand turns the pickup tube is still going to be flat with the plane of oil level. An exception to this MIGHT BE hard RIGHT HAND TURNS. A right hand turn would cause oil to slosh the opposite direction of the slanted cut of the oil pickup tube. If even the slightest edge of the tube becomes uncovered you suck up air. Again, the pan should be pretty damn full if you run 1/2qt overfilled... Even the M2 uses the same pan and a slightly modified pickup tube. No special baffles or anything.

The only other explanation to me is that oil didn't drain back to the pan fast enough. Or, oil doesn't drain down into the rear of the pan, where the pickup is, under high g-forces and a forward pitch of the motor. There is not much you can do about that. Some cars (even BMWs) run a dual pickup tube that will pull oil from both the front and the rear of the oil pan to prevent this type of issue... That is hardly something that should be necessary for 99% of people and an Accusump would be cheaper and easier insurance.

So, if it's not an oil weight thing then what else could it be. Maybe rod bolt stretch? Heat caused metal to expand (not likely as temps were not bad)? Foreign objects like dirt? Nope my motor was damn clean inside... Maybe a failed OFHG? VERY POSSIBLE as I just changed the OFHG but I also saw no sings of coolant in the oil but maybe with how hot the oil was on track it was burning right off? Fuel Dilution? Not likely on an N55 and no other signs present. I have never seen the AFR "hang" in off-throttle situations either.

I drained out 7qts of oil. It was full. No metal anywhere except in the oil filter but damn my bearings were burnt and welded to the crank. I'll be putting in an ACCUSUMP for the rebuild because this looks to me like a case of sudden loss of oiling for whatever reason... DME shows no codes of oil pressure loss. Unfortunately, I was using the OBD to get video data when it happened and not MHD logging data.

And you never consider detonation or tuning love it

You have a wider band map which means you are probably running over 20 PSI.. I dont think the heavily tuned cases of rod bearing fails should be considered Why ? Because way too many variables..

[bbnks2]

Originally Posted by Pladi

And you never consider detonation or tuning love it

You have a wider band map which means you are probably running over 20 PSI.. I dont think the heavily tuned cases of rod bearing fails should be considered Why ? Because way too many variables..

I was running a shelf map peaking about 18psi. Detonation could've been an issue but I didn't log how the car was running on the shelf tune on this particular day. I did stop at a really shitty no-name gas station on the way to the track. I have never had knock issues running the OTS MHD maps though.

Also, the rod bearing wear indicates an oiling issue based on how they look and how they are burnt. I don't think detonation would just cause the entire bottom end to loose oil flow and melt. Detonation would wreck bearings over time and probably on 1 or 2 cylinders more than another. Pistons, valves, and plugs all look normal. No abnormal cylinder wear at all actually. I'll make a post with pictures eventually but I am kind of busy right now with the rebuild lol

I fully agree that when this happens on a road-course, in an advanced HPDE session, and with r-comp tires that this is NOT a normal incident. Pocono killed 2 other N5x in the past few weeks. One a 2012 N55 and one a N54. Both threw rods. That is what interests me... what is it about this track that seems to cause failures. Only difference I see is the NASCAR straight and the ability to top out 5th gear... I have never hit 140mph on another track. I am trying to learn what I can so it doesn't happen again. I'll surely be back to the track.

I also have a 12/2010 build date 2011 N55 which fits the conspiracy theory so whatever you want me to show you in the opened up motor let me know. Nothing looks abnormal though to say there is some kind of flaw. If you want to play guessing games as to why an unmodified low mileage street car might've spun its bearings then go for it, but there is no way you're finding any kind of significant trend. It happens. Production tolerances vary. That's why warranty's exist. I've seen cars of every make/model be flat-bedded off the track with blown motors.

[SnapCoupe]

Originally Posted by bbnks2

I don't think 15 people with 0 automotive engineering expertise on a forum are going to find some technical flaw in the motor or BMW's recommendation.

My own personal theory is that this is a very tight tolerance motor with very high oil volume/flow requirements. The oil spec'd is perfectly fine for 99% of the consumer market. Put the car into a performance situation though and now consider what happens when topping out 4th or 5th gear and/or doing some high g-force turns...

Extended time at high revs = high volumes of oil flow and thick oil = oil that doesn't drain back to the pan very well. Thinner oil like a 20-30wt would help with this situation (if my theory is accurate). Oil flow protects bearings not pressure. Thicker oil produces nice high oil pressure, but at high rpms it means less FLOW due to pumping losses of the thicker fluid. Thinner oil would flow better at high rpm but might also require driving the oil pump harder to produce the same PRESSURE. I believe these cars do have some overhead in that area... we run a fairly beefy oil pump. The oil would be able to drain back to the pan faster and bearings with tight tolerances would be better protected with adequate FLOW to maintain the oil wedge.

Again, we need an actual engineer to weigh in because I could be way off base with these comments. Preferably one that has some experience tearing down these motors. I think I read somewhere by ABR or MMP or someone who has a rebuild program that side-play allows oil to escape the bearing race too easily? That changes the scenario entirely. I have never measured these clearances. I base my comments on seeing BMW shooting for a rod bearing clearance of .00135" (with an allowable threshold of between .0007" and .002") and also BMW switching their allowed oils for "M" motors to 5-30wt. They surely aren't recommending anyone run thicker oils... A high quality 30wt oil can provide the same film strength and shear resistance as a 40wt oil. Castrol edge is a perfect example. Both their LL-01 "European formula" 0-30 and 0-40 oils have the same HTHS rating of 3.5cp. The 0-30wt will just flow a bit better through the motor.

I have my motor torn down right now. I spun a rod bearing on track. Looks like oil starvation locked the motor up almost instantly. But, looking at the oil pan, I can't see how it could've been from oil sloshing OUT of the oil pickup area. It is very deep with vertical walls. Once the oil is down there it is not sloshing out. The pickup is even slanted so that in hard Left hand turns the pickup tube is still going to be flat with the plane of oil level. An exception to this MIGHT BE hard RIGHT HAND TURNS. A right hand turn would cause oil to slosh the opposite direction of the slanted cut of the oil pickup tube. If even the slightest edge of the tube becomes uncovered you suck up air. Again, the pan should be pretty damn full if you run 1/2qt overfilled... Even the M2 uses the same pan and a slightly modified pickup tube. No special baffles or anything.

The only other explanation to me is that oil didn't drain back to the pan fast enough. Or, oil doesn't drain down into the rear of the pan, where the pickup is, under high g-forces and a forward pitch of the motor. There is not much you can do about that. Some cars (even BMWs) run a dual pickup tube that will pull oil from both the front and the rear of the oil pan to prevent this type of issue... That is hardly something that should be necessary for 99% of people and an Accusump would be cheaper and easier insurance.

So, if it's not an oil weight thing then what else could it be. Maybe rod bolt stretch? Heat caused metal to expand (not likely as temps were not bad)? Foreign objects like dirt? Nope my motor was damn clean inside... Maybe a failed OFHG? VERY POSSIBLE as I just changed the OFHG but I also saw no sings of coolant in the oil but maybe with how hot the oil was on track it was burning right off? Fuel Dilution? Not likely on an N55 and no other signs present. I have never seen the AFR "hang" in off-throttle situations either.

I drained out 7qts of oil. It was full. No metal anywhere except in the oil filter but damn my bearings were burnt and welded to the crank. I'll be putting in an ACCUSUMP for the rebuild because this looks to me like a case of sudden loss of oiling for whatever reason... DME shows no codes of oil pressure loss. Unfortunately, I was using the OBD to get video data when it happened and not MHD logging data.

Interesting points that you bring. When my motor seized, it was near the top of the rev range (5500+ RPM) in second gear, coming out of a left hand corner. My OFHG and OFCG was replaced a month prior. The car also had an oil change a week prior and was full with oil. Oil starvation is an interesting and plausible cause that might be worth looking into.

[rich_mane]

When I worked at the dealership, we only saw a handful of locked up N55s. And almost every single one of them was within a few hundred miles of having their OFHG replaced. We even had it happen once or twice where the tech would replace the gaskets and take it for a spin, and the motor would lock up on the test drive. I'm not sure if they were beating on the motors or what, but have noticed that a lot of these failures come right after the service of the OFHG. Maybe something foreign getting into the filtered oil port and blocking an oil squirter like I've seen mentioned in some other threads like this one:

https://www.1addicts.com/forums/show....php?t=1359507

[xxMike61]

How big or small would something have to be to go into the engine without being noticed?

[northbranchroad]

Originally Posted by SnapCoupe

Interesting points that you bring. When my motor seized, it was near the top of the rev range (5500+ RPM) in second gear, coming out of a left hand corner. My OFHG and OFCG was replaced a month prior. The car also had an oil change a week prior and was full with oil. Oil starvation is an interesting and plausible cause that might be worth looking into.

Sorry if you already mentioned this, but what was your build date?

[SnapCoupe]

Originally Posted by northbranchroad

Sorry if you already mentioned this, but what was your build date?

October 2010

[maddmatth]

Did you guys find your coolant needed to be topped up occasionally even if there were no visible leaks? Did it ever spray from the coolant cap?

[fatty335]

Originally Posted by maddmatth

Did you guys find your coolant needed to be topped up occasionally even if there were no visible leaks? Did it ever spray from the coolant cap?

I check my coolant at every oil change and I always need to add a "touch" to bring it back up to the full ledge - as I understand it from the techs I've spoken with, this is pretty normal across n55 enterprise. No spraying from the cap ever. As it pertains to a spun bearing, I would expect very small amounts of coolant or other moisture in the oil to boil off during the course of normal driving. A large amount of coolant in the oil however (like during an OFHG service) could be trouble. Perhaps a recommendation of an oil and filter change in conjunction with the OFHG service - just in case coolant or any foreign matter was introduced - should be the standard?

[maddmatth]

Hmm think that shoots down my theory then. The loose headbolt would lead to more obvious coolant loss than that I think. I needed to top up coolant a couple of times between changes.

[TZANIDO777]

Oil starvation is def a concern for me. I have logged oil pressure at several tracks across the northeast from Summit point to Mont Tremblant in Canada and there is always one or two spots on track where I am seeing less than 10psi of oil pressure but at very low rpms, say 3-4k.

[Pladi]

Originally Posted by TZANIDO777

Oil starvation is def a concern for me. I have logged oil pressure at several tracks across the northeast from Summit point to Mont Tremblant in Canada and there is always one or two spots on track where I am seeing less than 10psi of oil pressure but at very low rpms, say 3-4k.

Less than 10 PSI ? Whaaat lol Hows your car running ?

My car logs over 80 PSI most of the time, thats crazy.

[bbnks2]

Originally Posted by TZANIDO777

Oil starvation is def a concern for me. I have logged oil pressure at several tracks across the northeast from Summit point to Mont Tremblant in Canada and there is always one or two spots on track where I am seeing less than 10psi of oil pressure but at very low rpms, say 3-4k.

Yeah time to put an accusump in. Rod bearings wont take that abuse forever.

[xxMike61]

How can I log oil pressure?

[Pladi]

Originally Posted by xxMike61

How can I log oil pressure?

MHD parameters for oil pressure are available. So MHD and monitoring add on.

[Welcome to NBA Jam]

Originally Posted by maddmatth

Did you guys find your coolant needed to be topped up occasionally even if there were no visible leaks? Did it ever spray from the coolant cap?

Yes, this is normal. While it is a sealed system, the coolant cap does vent. Coolant can escape through this, though it should not spray.

Coolant top offs should be very minimal: going from max to min over the course of a full year would be a normal loss.

[TZANIDO777]

Originally Posted by Pladi

Less than 10 PSI ? Whaaat lol Hows your car running ?

My car logs over 80 PSI most of the time, thats crazy.

Funny you should ask as I spun a rod bearing in Canada in the beginning of this month lol But I see less than 10psi for just that short amount of time while the car is loaded up, I also see 60-80 psi 98% of the time while on track. The problem got worse once going to a full slick.

Not 100% if its because of oil starvation yet because I did over rev the car during the first session on Saturday so could also be due to rod bolt stretch but weird stuff just started happening after that.

Car still turns on and runs but you can def hear the rod knock. Have not had a chance to open the engine up but will likely being going with a rebuilt engine from either MMP or ABR Houston if its confirmed a spun bearing and the crank shaft is scored which is likely the case.

[TZANIDO777]

Originally Posted by bbnks2

Yeah time to put an accusump in. Rod bearings wont take that abuse forever.

I am slightly skeptical about plumbing in an accusump as I remember reading that it does not entirely address the issue and is only a band aid.

I know VAC makes a baffle for our oil pan but have never seen a dry sump for our cars which is what we really need. Albeit would be expensive but two blown engines would cost you roughly one dry sump assuming you blow two engines lol