JET951

hi,
sorry if this is a topic bought up so often but i thought everyone would like to hear what i say about my experience with porsche cars( i have posted this in the 911 section as well as the 928 forum because i believe it to be important)

little bit of my history before i give you my findings.
MY name is Sean Buchanan, i work with my father Bruce Buchanan who has been working on porsche cars since 1977. I started as an apprentice and now six years later i am a qualified motor mechanic specializing in porsche. (all models)
you must excuse me as my post will not only deal with just 944etc, but all porsche cars of the era.

lets start with the early 944 single cam, twin cam engines. we have heard over the past six years of a lot of damage and worn engines and have noticed a pattern emerging that is a real pitty and completely unnecessary.

we service and maintain a lot of single and twin cam 944 models and we have had no engine wear at all when using a grade of oil that these engines were designed to run on. remember the 944 single cam was based on the 928 that was released in 1977 and early design work for these motors were in the late 60s early 70s.

we have read of lots of twin cam 944 models with worn cam lobes, lifter faces and mainly cam chain sprockets and chains. remember these surfaces are not pressure feed with oil, its only splash, and we have had NO wear problems with our customer cars with well over 250 000km's running on a
25-50 oil.

Simon Greenwood, a good friend of ours, who owns an indipendant porsche repair workshop has, at this moment, a 1989 944 turbo that the owner has been running a 5-40 synthetic oil(changed every 8000km's) for the past 30 000km's and all 4 cylinders and pistons are worn out. simon has had the engine bored out to accept oversize pistons and advised the customer to run a 20-50 or 25-50. this vehicle is running standard boost and had only 120,000km's.

A perfect example of this modern day sympton of using oils that simply dont work in the long run is 928 thrust bearing wear, this is a very new problem to us. and we have been working on 928s for a long time.a check we have been doing for a long time is as follows...

928 thrust bearing clearence check(axial play) 928 all models. using dial guage since may 04 to november 05

in this time we have had 52 new customer and pre purchase inspection 928s(all models) come into our workshop. the total number where it can be determined that the engine had been running on a 5-40 or lower viscosity oil was a total of 31 vehicles.
of these 31 cars all of them are on or exeeding the spec clearence. 2 of these cars are on their wear limit and will have to be dismantled very soon and be rebuilt and both of these had done approx
80 000- 100 000km's on these thin oils.

928 customer cars that we know and that have serviced for years and have been running on valvoline GP50( formally know as turbo V) 25-50, 42 cars in all most with 150 000km's and above were all within spec. (actually low to midrange wear)
the spec for these cars is 0.06-0.192mm = within tolerance
0.40= wear limit

911 3.0litre 3.2litre 964 3.6litre...
we have noticed that if 964 or ealier 911 models arew driven in city conditions with an oil which is less than 15-50 then oil pressure at idle when hot is nearly always too low and valve guide wear occurs in less km's. and on a 5-40 oil the engine is noticably mechanically noisier and causes oil leaks faster then a thicker oil.

928 all models...
5-40 oils= engine noticeable noisier, valve guide wear increased, cam chain sprockets and chains and lobes(twin cam) excessive wear, thrust bearing wear excessive.

this is not a complex subject like some people make it out to be. for example: any engine running at idle has pressurized oil running through the crank into the main and big end bearings. Now the only substance between the bearings and the crank(say main bearings) is the pressurized oil, when that oil looses too much oil pressure( such is caused by too thin a oil for the application or high load or mechanically over revving) it will cause the bearing to come into contact with the crank...thats metal to metal... which means Spun Bearing(damage). we have heard of a few 964 having this problem.

remember this is only my and my fathers opinion and we work six days a week on porsche motor cars. and these are facts. this is what we hav seen and experienced. to me the solution is clear. but it is your cars we are talking about, and thats your decision to use which oil is best.

thankyou for reading,
Sean Buchanan

sca037

Thanks Sean.

Brian

hosrom_951

My car just loves the 15w-50 grade, fully synthetic offcourse......

I used to run 0w-40 for 1 year, since i could not find 15w-50 grade. Yes, it was noiser, mostly at the cam housing area (lifters and probably camshaft).

15w-50 made the car run much smoother and quieter than before

RI Fast Eddie

So bottom line this for me. What is the best oil weight/viscosity to run in our cars? How does temperature play into this? According to the manual my S2 will run fine on 5-30 or 5-40 oil in my temperature range (Northeast US). Should I switch out my oil to a 15-50 or a 20-50?

sm

What oil do you recommend for the people who see 0 degree weather in the winter time and whose motors won't start with 15w-50 oil?

eohrnberger

Good info. Thanks Sean.

Re-enforces my decision to switch to Mobil-1 15W 50. I was running thinner stuff, but it kept dissapearing (and not on the floor either), and I too noticed the drop in pressure at hot idle, which I didn't like.

Now I just wonder how much damage I did while running the 3 DE's this summer. Guess I won't know until I tear it down for rebuild.

Mighty Shilling

Here's what I do... 15W-50 Mobil 1 for the summer... because that stuff becomes nearly solid in the cold, I run 0W-40 Mobil 1 in the winter months. Starts every time, no noticable problems.

500

Sean,

Great post. Factual data is always valuable. I was wondering if you can expand on those 52 928s that you inspected for thrust bearing clearance. Of the remaining 21 cars that would not have been using a 5-40 oil, were they all OK? I know you mentioned that long-time cars that you regularly worked on were OK, I was more specifically wondering about these other 21.

Great stuff!

Thanks,

Allan

JET951

the 928s we found had not been running on thin oils such as 5-40 etc were all within spec(thrust bearing) just like the 928 that we have been running 25-50 the wear was all low to midrange wear. i just cant see this as a coincidence... there is just too much evidence towards oil for us.
what is your temp range where you live R1 fast eddie

RI Fast Eddie

Sean - winter months in Rhode Island run from -5 to 30 F and summer months from 65 to 90 F. In metric thats -21C to 2C in the winter and 18C to 32C in summer months. The PO in the same climate region was runnig 5-30 oil all year round (the car gets stored for most of the winter but started occassionally to keep everything running). Any recommendations? Thanks.

yellowline

My plan exactly. Except this time, nobody had the 0W-40, so I went with M1 5W-40. If we have to run our engines with this kind of oil due to the cold, do you think we should we try to keep them at a lower RPM to further reduce wear?

SamGrant951

I cant get any 5w40 around where I live so Im going to mix some 0w40 and 15w50 (more of the 0w40) for my M3 this winter - I will not run 0w40 after seeing what my oilpress was like in the 951 - ran that stuff once and never again. The Porsche gets 15w50 synth or 20w50 dino year round (3 season car.)

yellowline

Now that I think of it, I saw a Castol 5W-50 that looked interesting. I figure it's just better to stick to Mobil 1, though.

Jfrahm

As for the 928 Thrust Bearing, I thought the cause of this was pressure on the crank from a creeping torque tube coupling? I suppose a thick oil, maybe with a lot of zinc in it might prevent serious thrust bearing wear int he short term, but I would think it's much better to check the coupling and release that pressure (and torque the coupler good.)

-Joel.

Jfrahm

Mobil 1 "Truck and SUV" is 5w40 synthetic. Shell rotella T synthetic is also 5w40 and is generally well liked (and cheap to boot.) However it is a Group III oil and only sorta synthetic. I put it in my Ducati for winter.

-Joel.