Porsche Enthusiasts Club Forum

I have thought long and hard where to put this post, we could maybe do with a general "technical discussion" area in the maintenance section, so if one gets created, can this be moved there?

For many years there have been arguments for and against the use of engine oil flushes.

Background info.
For those that do not know, an engine oil flush, is normally an additive that is added to the used engine oil before it is drained, normally involving the engine being run for 10 to 15 mins with the additive in place before the engine oil is drained.

Traditional arguments for.

That carbon deposits inside the engine oil system and inside a turbo, build up and engine oil can not dissolve them
That sludge (black death) will build up inside the engine and can not be removed with normal engine oil
That contamination and dirt will settle out of normal engine oil and not be held in suspension, so will not be completely removed by a simple oil change
That dirt remaining in the engine after an engine oil change will just re-contaminate the fresh oil
That sticking lifters and other engine components, such as oil squirters will be free'ed up with a flush
That flushing additives solves one or more, or even all of the above issues.

Traditional arguments against.

The additive will reduce the lubricating qualities of the engine oil, so damage may occur while the engine in run with it in place.
The additive will not remove any deposits
The additive may damage seals or gaskets
The additive may dislodge sludge which is currently helping poor seals to seal the engine
The additive remaining after a flush may reduce the effectiveness of the new engine oil
The additive is snake oil and just a waste of money

I would be interested in bringing this subject out and into the open, as many people have in the past seen arguments for, and against, but rarely in one thread, but as a side line.

I have my own views, but please do not be afraid to speak up about your views, everyone's views are important. Likewise do not be afraid to disagree with me or anyone else.

I have used Wynns Engine flush once or twice, the internet was awash with all sorts about it so I elected to use it on one mercedes engine that had been sat for years and was clearly gunked up when inspecting the camshaft area. Result was good.

I have not used it as a matter of course when servcing the cars, since there was no firm answer I opted for if it aint broke, dont fix it!

Interested to hear the discussion

Well I was really against flushes of any kind.

In fact I used to be against any kind of additive full stop.

But I was converted by a demonstration by a Forte rep who badgered me into running an experiment on one of my 968's several years ago and I was converted on the spot and use them on our "signature services" ever since. We do not on our factory services, simply because they are "strictly factory" as the main dealer would perform them.

think it just depends on how sludged up the engine is, if it is bad(probably caused because its an old engine and may be in poor condition anyway)the effects of flushing can be a double edged sword, some of the deposits maybe all that is giving the engine any compression, cleaning out the ring lands may just bring forward the rebuild date. Turbo seals etc can also suffer from being chemically cleaned . I dont know that much about oil composition these days, but I think many of the modern oils now contain much better inhibitors and detergents than they used to therefor reducing the sludging effect, these improvements have been driven I should imagine from the massive increase in recent times of the use of diesel engines and these oils have been developed for them, and through into petrol motors. I have not seen a badly sludged diesel for years, as long as it has been maintained correctly. I am on balance against flushing, but there will always be the older 'unloved' motor that may benifit.

Is it the case that a flush could help improve an old engine that had been mistreated for many years, not run very often, never had an oil change etc?

However, what about a car that you know has had fresh oil every few thousand miles, twice a year for it's whole life and is run pretty much every day? Could a car like that still be gummed up and see an improvement after a flush?

Yes I've always thought the regular use (daily) with regular oil change (6000 miles) car is always a better buy than a low mileage garage 'queen' that just sits until the summer... does make me smile how much trouble our American cousins have on their 968 website as their low mileage examples sit arround 10 months of the year unused....... any thoughts on this 'sea foam' product that gets talked about over there? sounds like the old redex treatment to me....

Hi All

I have used the Forte flushes and other Forte products for years....

They are REALLY good, so I would always recommend a flush, maybe not yearly but certainly every two years, particularly if your car doesnt get driven much, as is the case with a lot of Porsches....

The only problem I have with oil flushes is that I am not certain the standard motor shop ones would work as well as the professional ones like Forte, an oil company rep once told me that as far as the ordinary motor shop ones go you might as well just add the equivalent amount of parrafin

All the best Brett

Years ago (late 70s) when I got a new (to me) car it would get a sump full of oil at the Garage Dad managed. This was a fleet of Morris diesel vans & the bulk tank was Shell Rotella. This was heavy with detergent & I'd run it for a couple of weeks, then dump it & replace filter & oil. The crud this would remove was amazing. Admittedly this was on old technology engines but it never did any of them any harm. The new oil would then remain clean for the 3K or so between services. This was especially important on a Fiat 850 Sport Coupe I ran because it didn't run a conventional filter but a centrifugal one.

These days with better oils & tighter tolerances I just tend to change the oil more often, so certainly yearly changes max or 3-6K miles max on a sump full. This negates super dooper synthetics as they are generally designed for long service intervals. Bare in mind that in the 70's an F1 engine would be running on a mineral oil probably Castrol GTX/Duckhams 20/50.
The other issue is that of reduced protection on very high spec oils as they have less ZDDP, which promotes high load wear of bits like cams.

ZDDP is a really interesting topic.

Still waiting for Mobil to let me know the definitive details on its inclusion in the 10w60 replacement for mobil1 15w50, which has 1200ppm of ZDDP.

Their online specs for the 10w60 list the quantity of phosphorous of a similar amount in the same spec position as the 15w50 listed it, but the two compounds are not the same.

Its either that or find a supplier of ZDDP ad add it like an additive to the cars that need it in the right quantities.

one of my customers is a forte rep...used one of here flushes...works very well...too well really...my main rear oil seal leaks weeps now....bugger!!!