[Soul_Glo]

This is not one of those "get German Castrol" threads.. the oil in my 2.5 seems to break down every 2,500 miles... it burns up to 1 quart/litre every 2,500 miles and every 1,000 miles there after. You may laugh and say that the oil change is taking care of itself.. Previously I have had:

- The valve cover has been replaced and gaskets
- Oil filter gasket changed
- Leaking rear main seal addressed
- Leaking injector that was causing oil thinning also addressed

Normally I change the oil every 3,000 miles but it would be nice to see some 2,000 miles more and change every 5-6k miles.

The manual specifies 0w30 for it... in the UK we hardly every see the need for a 0 weight oil but that it is what it has had since new...

The stealer suggested changing to a 10w40 oil instead... he was clearly misinformed as he was saying that a 10 is thinner than 0 in cold conditions... However... I did run a 2.0 Turbo engine once... that was burning oil at 1 litre every 1500 miles (at 65,000 mileage) and it made no difference whatsoever...

Could this be a sick experiment? Do you advise against it? Any truth to having a 10w40 instead?

I am currently on 72,000 miles.

Cheers.

[TheSt|G]

It certainly is possible you could eliminate oil burning by switching to a heavier oil, but that doesn't address the actual issue or the increased wear of doing so.

[Phil325i]

In the UK anything from 0W-40 to 5W-30 should be fine (I've used Mobil 1 at both viscosities). But I don't think you should be burning that much oil at your mileage. I have a 325i (admittedly an N53 3.0) and I don't put a drop in between changes (every 6,000 miles). The electronic 'dipstick' stays at max throughout...

[AceOnShake]

Snake oil is the best oil

[rhombus]

Originally Posted by Broken_Gearbox

This is not one of those "get German Castrol" threads.. the oil in my 2.5 seems to break down every 2,500 miles... it burns up to 1 quart/litre every 2,500 miles and every 1,000 miles there after. You may laugh and say that the oil change is taking care of itself.. Previously I have had:

- The valve cover has been replaced and gaskets
- Oil filter gasket changed
- Leaking rear main seal addressed
- Leaking injector that was causing oil thinning also addressed

Normally I change the oil every 3,000 miles but it would be nice to see some 2,000 miles more and change every 5-6k miles.

The manual specifies 0w30 for it... in the UK we hardly every see the need for a 0 weight oil but that it is what it has had since new...

The stealer suggested changing to a 10w40 oil instead... he was clearly misinformed as he was saying that a 10 is thinner than 0 in cold conditions... However... I did run a 2.0 Turbo engine once... that was burning oil at 1 litre every 1500 miles (at 65,000 mileage) and it made no difference whatsoever...

Could this be a sick experiment? Do you advise against it? Any truth to having a 10w40 instead?

I am currently on 72,000 miles.

Cheers.

I would not go with the 10W as you will have more startup wear and more wear before the engine is up to temp (hard to tell without a coolant/oil temp gauge). 0W-40 or 5W-40 is what I would use. They end up the same warm viscosity but are made from a thinner base stock (0 or 5) which improves cold start flow/protection. Plus the actual oil molecules of a 10 base stock can be larger than a 0 or 5. Most engine wear happens when the oil is cold, before it is warm enough to flow, protect and cool.

The engine's tolerances were designed around a thinner base stock so that is what I would use. I would check the oil separator to make sure it and all of the hoses are in good working order. Could be the cause of your excess oil consumption.

[GORDON.M3]

Lubromoly 5w40 toptech.

[Soul_Glo]

The compression results were as follows:

Cylinder 1: 120psi
Cylinder 2: 115psi
Cylinder 3: 120psi
Cylinder 4: 120psi
Cylinder 5: 115psi
Cylinder 6: 120psi

The pressures appear to be within spec.
Both wet and dry tests were carried out.

There was a slight bit of hiss heard from the exhaust valves but the tech did not appeared to be concerned about it.

On a previous B25 we tore the engine down and replaced bad piston rings but these rings appear fine.

It's not like I red line it or push it really hard so I was scratching my head on how a 5w40 could help. Hmmmm

Next up I am wondering if it is worth having an oil analysis.

[GORDON.M3]

I have a N52B25, 200,000KM with Lubromoly no issues what-so-ever.
Aside from the common valve cover gasket leaks, and failing small parts like vanos solenoids the car drives like new after replacing them.

[Soul_Glo]

Originally Posted by gordon@

I have a N52B25, 200,000KM with Lubromoly no issues what-so-ever.
Aside from the common valve cover gasket leaks, and failing small parts like vanos solenoids the car drives like new after replacing them.

Thanks will look into the liquimoly

Having read up this may help to extend the breakdown by 1,000 miles... will give it a try. I once tried a synthetic blend with loads of esters that promised a delay in breakdown on an Audi 2.0T and it broke down quicker than a normal synthetic... it may be an interesting experiment to see if that is not the case here.

I found some threads on the check valve/vanos... I will look into those over the next few weeks.

[SDemetris]

Liquimoly is expensive... I suppose less than a new engine, but still... My boss last year who built IMSA cars swore by amsoil. Ive never tried it, but if youre looking to experiment, thats my suggestion

[GORDON.M3]

Originally Posted by SDemetris

Liquimoly is expensive... I suppose less than a new engine, but still... My boss last year who built IMSA cars swore by amsoil. Ive never tried it, but if youre looking to experiment, thats my suggestion

Liquimoly is cheap in Canada... I can get it for $34/5L over here.

[StealYourFace]

No rea data to back it up, but my car has 165,000 miles on it, and the last 80,000 have been with Mobil 1 0w40. The car sees track time, very cold winters and abusive stop and go driving.

Runs quieter than when I was using the BMW oil.. but that may be in my head because I like saving $$ (22 bucks for 5 quarts!) I cage it every 8000-10,000 miles or so, and change the oil filter half way between there once extra. I do change it before an hpde if it's been more than a couple thousand miles though.