wino5150

I am being told to run 20/50 Max Life in my '91 GT with 62K miles. The car was recently purchased from a single owner who only ran 10/30 Mobil One. I have been told by countless mechanics and the one who now works on mine (whom I respect greatly) that synthetic will 'leech' out of the engine and it is unecessary if you change your oil every 2-3K miles. I have looked at all the research on Mobile One, AMSOIL, Red Line, etc. and was wondering what peoples thoughts were. I know they're like buttholes... everybody has one. Otherwise, this car may be a test to see how much sludge or engine trouble 20/50 gives me. In the winter (I live in NC), I am planning to run 15/40 if necessary. I need to review the temperature charts.

Much thanks and well wishes....

Wino

Garth S

There's some good reading on lubricants here http://www.landsharkoz.com/techtips.htm
Also, search author Doug Hillary for some excellent studies of syn engine oil in 928s.
0W-40 is growing in use, although I generally use 5W-50 syn: Change intervals are signifigantly greater than 3K miles.

mark kibort

mechanics are not petrochemical engineers, nor are they engineers PERIOD. they usually know much less than most of the fellows on this list about these kinds of things.
Sludge?? i have yet to see a well taken care of 928 with sludge in the engine. Use redline or redline and be confident you are doing the best for your shark.

who better not to ask, than the guys that are regularly beating the snot out of the 928s on the track and street, and yanking apart engines to see what is worn. (usually nothing!)

mk

TeufelHei

Most wear (according to some experts) occurs within the first 1500 miles, something to do with oil chemistry. In any event, you've got a 10 qt system and a really good filter, kinda pricey to be replacing oil at $60+ per oil change.

From what I've been told, you can (should) go about 10k on a quality Synthetic and change the filter every 5k or so. This of course depends on driving type (agressive light to light type, or spinning the odo gear GT style). Racing is a whole other animal. Also, the word on the street is semi-annual oil changes regardless of mileage. Makes sense to me, plus it gets me out of the house and keeps me off the street at least twice a year.

I run Valvoline Full Synthetic since I can't afford the Redline/BG/Royal Purple stuff. Also, the folks at DEVEK think well enough of it to recommend it to people who may suffer from "excessive" oil consumption (ie ingestion) at high RPM. Not really a problem for me, but I like thinking I'm smarter than everyone else.

I'll probably go with M1 15w-50 after this though. Heck it's even less expensive at Wal-Mart ($3.70/qt). If not, Doug recommends a full synthetic diesle oil (Delvac 15w-40), and he's got the proof to back it up.

As far as leaking more with synthetics, if your seals are marginal already then there is an opportunity for some synthetic oils (don't ask which) to seep through.

However, dino juice is good too, and Valvoline Max life is my preference simply based on the seal conditioning additives the put in. As evidence, I changed my wifes former car to V Max Life after a steady diet of "whatever brand they put in at the gas station" for over 185,000 miles. There was minor oil consumption going on which was remedied by this change alone. If you've got a problem that's bad enough for engine work, then oil ain't gonna solve it. On the other hand, it might buy you a little time, and the insurance never hurts. It's what preventative maintenance is all about right?

TeufelHei

I'm also assuming you live in Asheville, NC. Lucky guy! I just realised upon moving to the left(ish) coast, I am out of the east coast feeding frenzy. Bummer.

Anyhow, seasonal changes will make a difference as well. I live in a dusty, hot, nasty, desert. Hence the 20w-50, regular filter change, and poor demeanor. You on the other hand live in a lush, beautiful, mountainscape that actually has seasons other than dry and wet. The point is, cooler weather will require you to run a lower viscosity oil if you want your cylinder walls, bearings, and valvetrain to last. Unless of course you like warming your car up for half an hour before you drive.

I'd suggest seasonal viscosity changes. Summer and spring run a mid range 15w-50 and use the 0w-40 stuff in the winter and fall. Mobile 1 has both, available in bulk at your friendly Wal-Mart super center. Call the big 3 for filters and enjoy!

By the way, the Blue Ridge Parkway is a federal road. Be careful out there, and be nice to Smokey.

Jim bailey - 928 International

The Porsche recommended oil change interval is 15,000 miles or once per year . Doug Hillary has by independant oil analysis PROVEN that oil in his S-4 was in GREAT condition after 15,000 miles ; search for his very informative posts on the subject . You are correct about their being no shortage of opinions when it comes to oil .......unfortunately most are based on little or no objective information and a lot of marketing Hype . Simply stated there is absolutely nothing to be gained by changing oil every 2,000-3,000 miles it is a waste of time , money and resources although that oil does hopefully get recycled .

hacker-pschorr

heinrich

No question ... you need oil in your 928.


Say, where can I buy Sunflower oil? (seriously) ... I find safflower, I find peanut, lingenberry, banana skin oil, snakeskin oil, and all manner of oils, even frankincense and myhrr .... but Sunflower oil, no.

Normy

Well, in 1992 I had a petro-chemical engineer from Korea as a student. Standing over the opened hood of my '85 VW Scirocco turbo...he told me that unless I had a high-boost turbo or a race car, that the advantages of synthetic oils were so small as to negate their cost. Basically, since then, I've been putting Castrol 20/50 in all my cars. My current 928 has a wet bottom, but only leaks small amounts on the garage floor. Last year I replaced the motor mounts and steering rack; I'm kicking the living **** out of myself now for NOT replacing the oil pan gasket, which could have been done very easily then! Susan even asked me over the phone "Are you going to replace this" and I'm like "It's not too bad yet". Famous last words with oil leaks!

N!

PS- I should have been Italian, based upon my liking for olive oil in cooking. My slavic ancesters got this one point wrong, I guess!

jej3

I just changed from the previous owners diet of dino to M1 15w50 last weekend and the engine started leaking like crazy.

I am going back to dino this weekend.

My .02

Greggles

Sounds like a commercial..... any afiliations?

hacker-pschorr

Every car I own is used for auto-x and the P-cars are used on the track. I figure why risk it. I'm going to start running redline in every car starting with each car's next oil change.

fst951

Actually Mark K. some mechanics are engineers. A mechanical engineer to be sure. Most of the people I graduated with couldn't change their own oil let alone tell you why oils fail or the real differences or benefits between conventional and synthetic oils.

I think most oils on the consumer market are just fine for your street driven 928. If you use a synthetic, you really only see longevity advantages, advantages in start up wear and very high heat advantages. Now those are important, but if you change your oil once a year because you put less that 10k miles a year on it, than you would be just fine with either.

Just a matter of money you want to spend and what needs you have to be met.

My opinion and as everyone know "opinions are like a$$holes, everybody has one".

Good luck.