anonymousagain

Amen !!
FWIW, black color in your oil indicates it is working to capture the "junk", not that it needs changing... similarly a pretty clear-caramel color after a few thousand miles doesn't mean the oil is good !

T6 Rotella 5w-40 in sunny but not too hot NorCal seems to work well, following Hillary's findings. Consistent gauge reading in hot traffic with A/C , no cold start noises and no deviation after extremely spirited driving. Oh and oil changes once per year after winter, with only Mahle filter - don't see the need to flush the $$ on mythical frequent changes.

Noted, if intending to run a DE day or constant lap duty, I'd change to XXw-50 and different brake pads, but spending the $$ for street use to deal with brief point-and-shoot stress is rediculous.

Can't wait to see the Blackstone report!!

dcrasta

I think the Oil pressure gauge is in Bars' atmosphere which translates to 14.5 psi at sealevel . This should be at least 2 bars at idle (~30 psi) and spike at ~ 70Psi off idle (> 3000 rpms)

dcrasta

Maybe if you drive less than 15000 miles per year ..

From Porsche's scheduled maintenance list :

• Required Every 15000 miles
• Change Engine Oil and Filter

Now granted , everyone under the sun claims the improved oil, better assembly and tighter tolerances lead to longer oil life, however (and some may disagree) when my oil turns really dark brown (ground coffee color) I cannot allow it to stay in my motor. I get paranoid because of all the motors I have had opened for friends that have been varnished and sludged inside. Even if they are not sludged to a high degree, the 'baked on varnish' look makes me worry. Maybe science and oil analysis will prove me wrong, but I just remember those old Fram oil commercials. Call me brainwashed, but I prefer to spend more changing my oil 4 times a year than some spun rod or camshaft issues (and when you are beating the motor up on Cars and Coffee drives you dont have any nagging guilt)..

Tons of youtube videos with cars with relatively low mileage that have sludge buildup. If you drive short distances and then let the car sit for long periods of time, oil can break down also. The only magic bullet is to keep the oil clean and fresh and this means changing it out and not falling for the false economy of going 10k, 15 miles between oil changes (unless you're using some exotic oils). Dino oil is pretty cheap considering the cost of a new engine.

YMMV.

dprantl

Has anyone ever seen sludge buildup inside a 928 engine? Oil change intervals also have to do with the volume of oil in the crankcase... An engine that has only 4 quarts almost always has a shorter change interval.

I also change my oil (always fully synthetic 15W-50) and filter once per year, and I drive about 10 - 12k miles in a year. I did the same thing with my previous 928. Altogether I have put over 120k miles on two 928's over 12 years as daily drivers and no issues. There used to be a site with a Camaro V8 or something that did regular oil analyses with M1 15W-50 and determined that at about 12k miles the oil needed to be changed.

Dan
'91 928GT S/C 475hp/460lb.ft

dcrasta

You make a good point about oil volume. Those little 4 quart sumps can barely keep up. I think the 32V 'supposedly' circulates a lot of oil (or the intention was) at high rpm's).

Definitely boils down to driving habits / miles and conditions. With your mileage figures I can see your interval being reasonable. My Daily drive is closer to 40+ per day with commute accounted for. Rush-hour on the highway can be rough on Oil. I don't beat up my car but I don't baby it either. With my commute plus weekend play I a (paranoid) oil change advocate.

YMMV.

IcemanG17

my experience:

Ran my street 928 for years on Mobil 1 15-50 with no issues....even tracked it twice that way :>(
I never had the oil tested

Ran my 1st race 928 for precisely 9 hours on track....on Amsoil racing 15-50 and the filter was full of metal..rod bearings were DEAD.....it later died due to faulty rebuild on Amsoil...not Amsoil fault

2nd race 928 blew up in 16 hours, but most of it was on crap walmart oil due to insane oil leaks we couldn't stop and excessive RPM

2nd race 928's 2nd engine ($300 used 117k engine) ROCKED......77 hours and counting with NO issues....only amsoil race 15-50..perfect oil analysis and great pressure all the time..still runs perfectly for new owner

3rd race 928 1st oil test just came back good......also Amsoil racing 15-50.....things are looking good!!!

jheis

An oil story - more real life anecdotes - ...

Fixed it for you.

andy-gts

Greg brown told me torco racing oil and change and evaluate regularly...oil pressure 1.5 bar hot and 4 bar above 2000rpm, Never has hit 5 bar since I bought it in 2006

mark kibort

greg brown is not an oil engineer. greg is a brilliant engine builder,

based on my experience, and this is more on track and street than anyone here, the oil should be hitting 5bar at 260+ oil temps, and if it doesnt, it might indicate viscosity break down. Plus there are other things that many of us, probalby most of us, dont understand.
I may have stumbed on Amsoi, based on its success in aviation applications, but it works and my experience proves it. use me, with multiple two valve, 4 valve applications, to show that the 928 can be raced with no issues with bearing wear. as brian has seen as well as Scot, and my 4-5 engines, no issues with oil analysis, and post racing engine tear downs have shown no wear issues, even after 8 solid years of racing in most every racing series possible. can you oil or designs match this?? if not, i would be inclinded to do what i have done and you just might have the same results.


Mine have never failed. the only diff, i dont re invent the wheel. i use the stock stff and dont rev over redline.

no blow by contraptions, no coolers, baffels, sumps, of any kinds. all stock stock stock and no issues, running at 108% of porsche GT3 times. with 335 to 370rwhp and 315/335 hoosier A, R or toyo tires.

take it for what its worth!

Mark

Speedtoys

"based on its success in aviation applications"
---
Ive -never- seen it for sale at any pilot shop.

Amsoil did produce an aviation oil about 10 to 15 years ago. It was taken off the market because it did not absorb the lead by-products of combustion.

This resulted in a build-up of gray tacky deposits in the ring belt and prop that caused control and oil consumption problems.

The company does not have an approved (by any manufacturer) product for aviation use.


Amsoil is a disaster in aviation use.

IcemanG17

VERY interesting.....

andy-gts

Mark,
I hear you man, I am an amsoil dealer and use the stuff in my other cars, I am sold on the full synthetic 25k oil and have had no problems...love the stuff.

Speedtoys

I was too narrow...

ANY automotive oil, especially the synthetics, are begging for problems in the air on engines using LL100 due to the nature of the wide tolerances and use of lead in the engines.

Mobil-1 lost their asses in the late 80s/early 90s on this..the chemistry differences are too far apart to mix the two worlds.

Engines approved for Mogas...entirely different story..sometimes...but I still would not use something the engine manuf. for aviation use didnt specifically recommend. Its just different in the air.

GregBBRD

Although I'm certainly not an oil engineer, which Mark has pointed out, I do have a bit of a background of making engines live, in extreme circumstances.

My background is Porsche engines (I started, originally, racing VW engines, in the late 1960's.) And Ford FE engines. And Chevy big blocks. And Chevy small blocks. I'm perfectly happy inside any of these engines.

Of all these engines, however, I think I "understand" the 928 engine better than all others. I have the background to be able to figure out what the Germans were doing....and enough background with Chevys/Ford engines to be able to apply lessons from those engines.

The combination seems to work, for me.

The one thing that I do know is that if an given engine has "higher" oil pressure with one kind of "fresh oil" than another kind of "fresh oil" (at the same 210 degree temperature) and both oils have the same viscosity rating....the oil that has the higher oil pressure is actually thicker and someone is "under rating" their oil. That's a given.

I also think that good oil is good oil.

In the "old days" I used nothing but Kendall GT 20-50 in my high output engines. Of course, that company was bought up and the oil changed. Rumor has it that "Brad Penn" now owns the rights to the "old" Kendall GT oil and that this is basically what they are selling. However, there was a large amount of time between the "loss of the original Kendall GT" and the "availability of Brad Penn".

So, I needed to come up with a different oil. I tried several oils and found that Torco gave me the results that I wanted. I wish I had unlimited funds and could test every product on the planet, but I don't...and I stopped "testing" for oils after I found Torco.

I've never poured Amsoil into anything. Ever. Mark Kibort has had great results with this oil. However, that being said, Mark doesn't run his engines the way I expect my engines to run. I don't tell my customers to shift at 6,000 rpms...and that would be silly, for Andy's car, which makes its peak horsepower at 7,200 rpms.

However, I would not expect there to be any issues with Amsoil compared to Torco. I'd encourage you (Andy) to try Amsoil (especially since you are a distributor) at your next oil change! I'd suggest that you do stay in the 20/50 viscosity range.

Let us know what the differences are. New data is always good!