Tony

Good stuff as usual Doug. Ive installed aftermarket oil and water temp gauges in my car and never "get on it" untill it gets "warmed" up. We even give our jet engines 3 minutes MINIMUM after start before applying takeoff power.

Ill have to go look for this

Giovanni

Okay, I am returning my Mobil 1 and get some Rotella. These are good for 3k or 5k miles intervals?

mark kibort

Doug,

I know you have been pretty level headed about the oil comparison, and appriciate the effort in providing the technical information.

I have seen some very parcular things happen to my engine and others when using mobil one, ONLY at extreme racing temps. the pressure goes down substantially, and this is something not seen during street driving conditions.

Im providing some real life, actual readings both in areas of temp vs pressure characteristics and time to warm up.

Im not a product basher normally, but when i saw the pressure in (2) 928s drop to near 1-2 bar on 100 degreeF days at the track, i was worried that that was not a good thing. changing the oil to amzoil 20-50 or redline, seemed to stop this problem completely (actually the oil pressure warning light would flicker on during low speed, low rpm turns!)

so, it would be nice to have someone do a track day and change the oil at the track and compare to verify what i have seen, or for someone to show some 260 degree temp vs viscosity break down charts of the differnet oils.

I understand the difference and blend of flow vs pressure. if the oil gets too thin, and the pressure goes down, even though the flow is good, there may not be a film of oil that is protecting things when they NEED to be protected. I know my amzoil at 260F thins out as well, but based on pressure readings over 5 years and 1000s of laps, at extreme track temps, ive never seen them fall below 5 bar, ever at high rpms! my water temp on those days is normal too.
Oil has been seen to be as high as 280 degree F on 100degree days at laguna where there are not as many high speed straights for cooling.

Most recently, the failure at Sebring, coupled with the low pressure indications, makes me very nervous about the performance of Mobil 1, for our cars, in high temp activities.


Mk


.

Bill Ball

Can we get Rotella synthetic 5-40 in the US?

I tried one 40 weight Castrol synthetic and had low pressure at idle at the end of an open road race. So, I feel more comfortable with 50 and have stayed with M1 15-50.

FotoVeloce

Yes, at Wallmart of all places and a great price too. I have jugs of it left from use in my motorcycles. I hesitate to put the 5-40 in my air-head Pcars but I've used the stuff in bikes. However in my track bikes I used 15-50 M1 with oil analysis and had excellent post-use results (now contamination, good film stregnth, etc.). I never had any oil analysis tests run on the bike that used the 5-40 just for lack of interest. Might have been a good thing to do though.

I'll be getting the PCar's oil checked here shorlty since they are due for changes right now. The only thing keeping me from changing the oil is the debate re: M1 and other oils (including the lower weight 5-40 rotella).

To re-iterate. I get my Rotella at WallyWorld.

Namvet

In the years 80 to 84, while sponsored by Valvoline in Stock Car racing, we often turned our short track Chevies 7800 to 8k and inspection on disassembly showed some Probs in Bearings,(not real serious), and since I had used Redline in my private racers, I began running it in both ST and Long track engines. Things looked better on teardown.

Today I ran my 84 928S real hard and pushed the tires to some high temps in 85 degree weather,, Oil pressure was stable and even at hot idle, the OP needle was steady at 35 lbs. She likes the Redline I use, and price is not a problem. Redline is simply the best yet.

namvet

Namvet

MARK!

I have assumed that you're NOT using a dry sump oil system on your car.

Dry Sump pumps are adjustible and give a margin of safety not available on OP Wet Sump systems.

Wish you well in your racing the 928.

namvet

chaadster

I can deal with the notion that one oil might be best for racing--based on Kibort's experience--and another best for street use--based on Hillary's examinations, so...what's the argument here about, guys!

To everyone just throwing out brand names, e.g. "nervous about Mobil 1","you can't beat Amzoil", "I'm gonna get some Rotella," be sure to include the formulation, e.g. 5w 40, in order to keep the discussion meaningful.

Gretch

Doug, based on your previous recommendations, I am using Delvac 5 W 40 in my whole fleet, including the diesels, trucks, cars. Everything but the Harley.....and it should prolly go in that too.

With the Rotella recommendation.... are you suggesting that I can do better then delvac?

mark kibort

no dry sump or even an accusump. i make sure the pan is always full, and generally drive the car smart at the track. (e.g. no need for 6000rpm, part throttle around a constant raduis, high g loading turn.)

thanks for the racing well wishes!

Mark

mark kibort

Of all the 928 #2-6 bearing failures Ive heard about, 10 of them have been with mobil 1, and one has been with amzoil.

i certainly dont think you can discount my observation of high temp themal break down of mobil 1 causing poor oil pressure readings during race conditions.

however, certainly there is a difference between street and track driving, not that mobil 1 is better for street driving, but you might not need a better oil for street driving.

As far as i know, ive been pushing a 928 harder and more frequently than anyone in the world and for a longer period of time. Do you know any other 928s racing for 5 years and 5 full seasons, not missing one event with the same engine? I think that kind of track record (pun intended) is worth looking at and attaching value to.

Mk

928ntslow

Mark, you are preaching to a street crowd which far outways the small percentage of racers....like maybe 100:1 or more. None of us will ever realize the effeccts that you are referrring to. I have used Mobil 1 since they had started making it. It is GREAT stuff no matter how you slice it. I don't even think they push the shelf product for anything other than street use. My F150 that I had purchased new in 1992 has had nothing but Mobil 1 since the day I have owned it. AND the same FRAM oil filter. Which incidentally, is KEY to any oiling system. It is more important than the oil itself! My truck now has over 305K miles and runs like a top! I ran the hell out of my 1982 928 with Mobil 1 all of the years I had it in the southern California heat...ran like a top!

I and others know you have learned and obtained quite a bit of knowledge in your racing and no one is disputing that or arguing with you over it, but quit baggin' on street products...especially Mobil 1...it's a top notch oil! You yourself should know these are two very different enviroments requiring differnt products.

anonymousagain

Gretch - Doug was NOT indicating Rotella was a superior choice to Delvac. He stated that Rotella is an excellent choice, with appropriate coverage in 5w-40 and attainability in the US (Wally-world, where Delvac 5w-40 is rather scarce if any). IIRC, Doug prefers Delvac as well and views it as "a smidgeon" better than Rotella...albeit a moot point if adhering to the yealy oil changes for our 928's.

Rotella for me, especialy since it's highly test rated and reasonably priced (haven't found Delvac in my area for $$ comparo). On a side note, I did find that Target clearanced the previous M1 stock in my area, so I now have ~17qts of 15w-50 at just under $3/ea to bleed off this summer (without concern)...then back to the Rotella. Then again, I may donate it to Bill Ball's ORR prep fund, since he's seen need for the 15w-50 at sustained 160+ speeds

Gretch

I get the Delvac by the gallon at Napa........... I run it in a fleet of 8 motors from diesels to hot rods. I am pretty sure I pay well less than $20 a gallon for it. When I buy it, it is usually a restock and I am picking up several cases of it...... They know I want it and keep it in stock, I usually clean them out of what they have.

Warren928

So it sounds like if you drive in hot temps and/or tend to beat the snot out of your car on occasion with redline shifts at higher temps, then for safety sake go with amsoil or redline. It holds its viscosity at higher temps and abuse more accurately, and that kinda makes sense. Amsoil was originally made for jet engines that cost $100k+ a piece, and maybe their level of [precision and tolerance of their product is showing thru in this exception.
I have used Mobil 1 in cars that don't get abused too often and did fine. It certainly had more viscosity stability than dino oil at high temps. My dino oil quickly turned into water in a hotrod I owned and caused a spun rod bearing after about 6 hours of flogging the engine over a weeks time.

I have been using Amsoil, and for the extra buck per quart, its not a big expense. Plus if you own alot of cars, buy a preferred membership and save 15-20%

My friend Mike has been an amsoil dealer for years, he is a really great guy and helpful,he's in New Hampshire, but sells everywhere: www.weareoil.com. Never had a problem with Mobil, but I wont take the chance on it in case my right foot gets too heavy on a hot day.