[pjs]

Oil change iminent, Dealer 1 says (at extra cost) Engine Flush is important for a 335i to help protect the twin turbo set up, Dealer 2 says that's a load of bull and hints that its just a good money maker!

Tony (or anyone) what exactly is an Engine Flush and what are the benefits (if any)

cheers in advance

[E92Fan]

Originally Posted by pjs

Oil change iminent, Dealer 1 says (at extra cost) Engine Flush is important for a 335i to help protect the twin turbo set up, Dealer 2 says that's a load of bull and hints that its just a good money maker!

Tony (or anyone) what exactly is an Engine Flush and what are the benefits (if any)

cheers in advance

Hahaha... dealer is trying to make a good bit of extra money!

An engine flush is basically putting a load of seafoam engine cleaner through the intake system to help to remove any oil or carbon deposts. It is debatable whether this actually helps OUR engines in the 335i. It is true that the 335i engine does suffer from carbonisation of the intake valves - this is most common on engines which consume a lot of oil and have had running problems in the past. We don't know how much of a difference the seafoam actually makes, given that the carbonisation is chemically adhered to the intake valve surfaces and a bit of cleaning foam will do nothing to remove it. Where 335i engines have suffered from this clogging up and BMW have stepped in to remedy the situation, each time the head has had to be sent off for chemical cleaning. If the Seafoam really did work, BMW would not have to resort to the expensive chemical process instead.

However your engine I believe has been stripped and rebuilt has it not? If I remember correctly it has new injectors and plugs and so forth. I would imagine your engine is running very well at the moment, so an engine flush won't be necessary. Why mess with something that doesn't need messing with?!

Out of curiosity, how much are they charging for an engine flush?

[pjs]

Originally Posted by E92Fan

Hahaha... dealer is trying to make a good bit of extra money!

An engine flush is basically putting a load of seafoam engine cleaner through the intake system to help to remove any oil or carbon deposts. It is debatable whether this actually helps OUR engines in the 335i. It is true that the 335i engine does suffer from carbonisation of the intake valves - this is most common on engines which consume a lot of oil and have had running problems in the past. We don't know how much of a difference the seafoam actually makes, given that the carbonisation is chemically adhered to the intake valve surfaces and a bit of cleaning foam will do nothing to remove it. Where 335i engines have suffered from this clogging up and BMW have stepped in to remedy the situation, each time the head has had to be sent off for chemical cleaning. If the Seafoam really did work, BMW would not have to resort to the expensive chemical process instead.

However your engine I believe has been stripped and rebuilt has it not? If I remember correctly it has new injectors and plugs and so forth. I would imagine your engine is running very well at the moment, so an engine flush won't be necessary. Why mess with something that doesn't need messing with?!

Out of curiosity, how much are they charging for an engine flush?

Cheers Tony for the instant response! Looks like its almost £100 for a flush (£125 diff between dealers for Oil Change, Microfilter and Front Pads). And with 6 new injectors, coils and plugs the engine has been in bits, and run sweet ever since.

Might try Mr Muscle in the oil a few days beforehand Much cheaper, probably as effective

[Giff]

Seafoam?

Many good garages use an engine flush, they drop the oil, refill with engine flush, run it to clean out the crap, drop it then refill with the correct spec oil.

Many think it is the holy grail of engine maintenance, it certainly keeps your oil cleaner for longer.

Some worry that it may loosen deposits that could go on to block oil passages etc, personally I love it and use a flush every other oil change.

[Mark II]

SeaFoam: http://www.seafoamsales.com/ The 1951 Ford in their advertising wouldn't encourage me to put it in a modern BMW

As Tony mentioned, only a proper de-coke will remove the hard deposits but I suspect there are many garages these days who, in a bid to raise their profits, will prey on the fears of conscientious & concerned owners to basically sell snake oil.

If it gives peace of mind then I guess there's no harm but personally I'd question whether there is any tangible benefit in engineering terms from using Seafoam / flushing oil in a well maintained modern engine (esp one that's using decent fuel and running fully synth oil through a good quality filter).

Better just to spend the money on an annual oil/filter change instead.

Just my tuppence tho'

[E92Fan]

Originally Posted by Mark II

SeaFoam: http://www.seafoamsales.com/

As Tony mentioned, only a proper de-coke will remove the hard deposits and I suspect there are many garages these days who, in a bid to raise their profits, will prey on the fears of conscientious & concerned owners to basically sell snake oil.

If it gives peace of mind then I guess there's no harm but personally I'd question whether there is any tangible benefit in engineering terms from using a flushing oil in a well maintained modern engine (esp one that's using decent fuel and running fully synth oil through a good quality filter).

Better just to spend the money on an annual oil/filter change instead.

Just my tuppence tho'

My tuppence also

[Giff]

I'm pretty sure the service the OP is being offered is an engine flush, nothing to do with seafoam...

[Ant Man]

I've always likened an engine flush to rinsing out one's bucket after cleaning the car. After tipping the dirty water down the drain there are lots of dirt particles left in the bucket. Giving it a good flush with clean water allows the removal of said particles.

[m1bjr]

Originally Posted by Ant Man

I've always likened an engine flush to rinsing out one's bucket after cleaning the car. After tipping the dirty water down the drain there are lots of dirt particles left in the bucket. Giving it a good flush with clean water allows the removal of said particles.

You have an oil filter for that

I agree, the engine flush that most garages tout is normally a temporary thin oil to remove crud.
We used to use a mix of clean engine oil and diesel to thin it 'back in the day'

However, the yanks seem to have picked up on an issue with petrol in the oil.
Thats a massive problem for a lubricant, upsets the chemistry badly.

It's a recognised issue with DI petrols, you could see more blow by at the rings.
And, I suspect why they think is a good idea to flush the system on a DI petrol car.

There's some fascinating reading about D.I. petrols and oil contamination by the real experts if you troll the web long enough.
Tests have shown (apparently) that the effectiveness of engine oils in these can be critically reduced in just a couple of thousand miles.
I know Audi had big problems like this so I did some reading long before I bought the 335i
So Im doing 5k oil changes off my own back.

HTH?
Steve

[Yahoo]

I have found petrol dilution to be a problem on mine. The last sample I did petrol made up 4% of the sample - which is pretty scary. Regular long runs and oil changes are important on the N54 imo.

[creepy coupe]

Tony, do you know how the carbonisations occurring? Being direct injection I'd have thought any fuel was metered into the cylinder after the valves were closed or very close to it. Or is it oil carbon burn up, or recycled gasses?

[doughboy]

Just my tuppence... It must be from the recylced crankcase gases / oil mist?

The recyled gases/oil mist are dumped back in to one intake tract (the rearward one I if remember) just after the airbox, so they get drawn through to the rear turbo compressor for cylinders 4,5 & 6, (probably making mess of that too), the through the intercooler, coating that in oil, and then in through the throttle body to finally carbon up the valves.

Of course with DI you don't benefit from the supposed detergent effect of fuel to keep valves and intakes ports clean.

[creepy coupe]

Originally Posted by doughboy

Just my tuppence... It must be from the recylced crankcase gases / oil mist?

The recyled gases/oil mist are dumped back in to one intake tract (the rearward one I if remember) just after the airbox, so they get drawn through to the rear turbo compressor for cylinders 4,5 & 6, (probably making mess of that too), the through the intercooler, coating that in oil, and then in through the throttle body to finally carbon up the valves.

Of course with DI you don't benefit from the supposed detergent effect of fuel to keep valves and intakes ports clean.

Going through the throttle body isn't such a good thing.