Brad writes:
Some years ago in an effort to quiet hydraulic lifters, I ran a quart of ATF in my Isuzu Trooper for 500 miles before I changed the oil. ATF supposedly has a bunch of detergents and this would clean out all the oil passages. I can tell you, the drained oil was the blackest I’d ever seen come out of one of my cars. It also seemed to help with the valve clatter, but didn’t completely cure it.
So here is my question . . . I’m getting close to an oil change in my 1988 911 Carrera, I was thinking of doing the same thing to it, to really clean out the engine. What do you think?
Sajeev replies:
Yup, ATF kicks serious sludge from an engine. The same is true for the famous Marvel Mystery Oil and a host of comparable engine cleaners. But that doesn’t mean I go out of my way to recommend them. Because I won’t.
I am wary of any high detergent “scrub,” mostly because the cleaning/desludging can create oil leaks around worn gaskets; or, it might dislodge a chunk o’ gunk which makes a new home on a crankshaft bearing. Worst of all, the increased friction of detergents means you run the risk of damaging your motor while the ATF circulates. Is it worth freeing a sticky lifter for this?
Of course, this is speaking in generalities. But using ATF on a fine running Porsche can be a serious financial burden on your wallet. Keep in mind that the motor in a Porsche is no (Isuzu) Trooper, and should be treated accordingly.
More to the point, you shouldn’t worry if you change oil on a regular basis: the motor will be tidy enough for decades to come.
[Send your technical queries to mehta@ttac.com]
What works in a low-revving truck engine isn’t necessarily good medicine in a high-performance, high RPM motor. Quite possibly the opposite.
Talk to an independent shop – they may have a product that will do the job.
—
Sajeev, were you meaning ‘wary’ when you wrote ‘weary’?
Please visit the LN Engineering website section on oil. They concentrate on air cooled Porsches.
http://www.lnengineering.com/oil.html
And with that, I’m off to an oil change for a Cayman S. Motul 8100 5W40, not Mobil 0W40.
The fastest way to clean the inside of that flat six:
Accelerate to highway speed; 70 to 80 mph in 4th gear.
Instead of upshifting to 5th; select 3rd gear. The valves will magically decarbonize the piston tops.
I had a trooper like that. Tough as hell truck. Put 300K+ on it with zero issues driving to Alaska and back years ago. I think I changed the plugs and oil, thats it. It was a 1986 pre-GM involvment.
The common thinking on sites like Bob Is The Oil Guy is that ATF does not help to clean the engine.
But, I have also heard stories from old-school mechanics who swear by this method, so I have been adding about 1/3 quart of ATF into the minivan engine a few days before oil changes. I do this every second oil change (5k mile intervals, whatever oil is on sale at Wal Mart).
At 100k miles, I had a small oil pan leak. When I pulled the pan to swap gaskets, the engine and pan were spotless inside. Is the 3.3L Chrysler motor just a clean engine, or did the ATF help? Not sure.
I will also tell you this – I don’t have the nerve to try the ATF trick on my wife’s Lex and probably would not try it on a Porsche either.
Do your Porsche a favor and just stay away from oil additives. They’re a waste of money at best, and can damage your engine at worst. Trust me, you don’t want to know what an engine rebuild or replacement would cost for your 911.
Instead, use high quality synthetic oil and a high quality filter, and change the oil at regular intervals (for 911s with their 12 quart dry sump oil system, and depending on how you use/abuse your car, this is generally quite a bit longer than for most other cars – consult your owners manual or a competent Porsche mechanic) and you’ll be fine.
“Fleet” diesel/gasoline dual-rated oils, such as Chevron Delo 400 and Shell Rotella T DO contain more detergents and dispersants than “for gasoline engines” motor oils. I suggest a drain and refill for a safe, gentle cleaning. In summer, 15W-40 should be a suitable grade for that Porsche. Rotella T is also available as a 5W-40 synthetic. Consult the owners manual.
Why this myth that ATF has high detergency is beyond me. Transmissions do not deal with blowby of combustion products and are essentially “sealed”.
I would heed Sajeev’s advice. Attempting to de-gunk the inside of an engine can create more problems than it solves. Especially if you’re not having any problems. You might end up having your engine cleaned at the shop as it soaks in the parts cleaning tank.
You can see for yourself the detergent properties of modern engine oil by this quick and easy method. Next time you check the oil in your engine use the drop off the end of the dipstick to clean off your fingertips the oil/dirt you just got from the filler cap.
roamer : Sajeev, were you meaning ‘wary’ when you wrote ‘weary’?
D’oh! Thank you for that.
Wary: marked by keen caution, cunning, and watchfulness especially in detecting and escaping danger
Rislone.
ATF does not have near the amount of detergents as engine oil. Engine oil receives carbon from combustion that gets past the rings. Trans is essentially a sealed system with small air breather to allow heat expansion.
Perhaps an oil change interval using Mobil 1 if you don’t use it already.
Not a cure-all but some believe the stuff can help dissolve and carry off a small amount of crud.
A couple doses of Techron shortly before the oil change will surely not hurt a thing and may assist in cleaning parts of the engine.
A few high-speed or high-rev runs (within reason) with the above chemicals coursing through the engine’s innards couldn’t hurt.
Cheap fixes never compensate for the efforts of a competent mechanic,
FYI, Ed Kollin, a former Exxon research chemist who has several other well known products under his belt (Rejex, ASL Camguard), analyzed MMO (Marvel Mystery Oil) and found:
MMO contains mineral spirits, 30 wt baseoil, red dye and wintergreen fragrance.
It could be the mineral spirts of MMO that helped remove sludge.
Although I’ve had good results with the 1qt ATF, 3qts regular, there was one time with a cleaner where it did indeed seem to dislodge something chunky.
Luckily, I stopped in time.
I’m with Nikita on this one: run a dual-rated 15W-40. High detergency and excellent engine protection.
OK….no adding ATF to the oil. I already use Mobil-1 full synthetic.
SSSOOOO………What about a Zinc additive?
I did use Marvel Mystery Oil in my old Oldsmobile with the 307 4B when it started to use oil around the 100,000 mile mark. It was burning a quart every 3000 miles and the Marvel stopped it. Kept it till 150,000 miles, but switched to Valvoline High Mileage Engine Oil when it came on the market.
1988.911.Carrera
Look at that LN Engineering website oil discussion. They review why they prefer some oils that meet an older API spec and discuss additives to bring up the ZDDP (Zn and P)levels. IIRC, they prefer finding an oil that has the proper ZDDP levels rather than an additive. ZDDP has been reduced in newer formulations because it fouls the catalytic converters. News to me – my 1991 C4 always blew nearly zeros on the emissions check even in 2008.
FWIW, their observations may apply equally to other high performance engines.
Some engines are more prone to collecting sludge than others. Short trips will also gunk up an engine. I favor 3-5 kmile OCIs I use the cheapest oil I can find. Current fav is Walmart Supertech 20w50 dino. At 330k miles , I pulled the valve cover on my 88 528e and found less than 1/4 cup of accumulated sludge. So I’m not buying into the hype about thin synthetic oils.
~tongue-in-cheek~
Has anyone considered using KaleCoAuto’s Engine Scrub?
~/tongue-in-cheek~