O god, 70K thats crazy ... My dad had a beater truck that leaked oil so since it got a fresh quart a week, it was changed maybe every 15K or so but the filter was changed more frequently ... I couldnt imagine going 70K though ...

FWIW, I run Mobil 1 5W-30. At cold start, I idle pretty high pressure (I want to say around 50psi?) and at hot idle, I still idle around 25PSI. This is the lowest the pressure ever drops, sitting in traffic, on a 90* day. I think running my oil cooler makes all the difference.

 

A/G ~ I guess I shhould have been more specific ... I was pointing more towards the fact that maybe Mobil just had better detergent properties versus CG ... I mean, who has proof that there was actually more wear? You would have to run two of the same filters, from the same lot, on the same motor, after it was cleaned out ...

Oil Analysis is still too much of an iffy subject because there are soo many underlying variables. Who knows if they didnt drive their car on a trip somewhere where it was dustier one time than the next or something like that. Its impossible to account for all variables. And I have seen some pretty nice analysis's from M1 as well ...

 

The "GM engineer" and Larry still seem to feel that 0W-30 oil is "thinner" than 10W-30. It is "thinner" at 0degF (actually, "0" weight oil is tested at -22degF, "5" at -13degF and "10" at -4degF). As the oils gradually heat up, the differences beween the 0W and 10W will gradually disappear (don't flog a cold engine). They are virtually the same viscosity at 212degF. They both need to understand that concept.

To repeat what I already pointed out..... With conventional motor oils, using the long chain polymers to achieve the wide range of viscosity vs. temperature, a 0W-30 may be slightly thinner at 212degF than a 10W-30 when new. And, because of mechanical and thermal degradation of the long chain polymers, the wide range viscosity conventional oils may thin more over their life. But with true synthetic oils, this is not the case. A 0W-30 and a 10W-30 will exhibit the same viscosity at 212degF when "new" and will hold these properties over a much longer life.

Here's an interesting link. The main problem is that a lot fo the data is from 1991, and it really dances around the issues of synthetic motor oils. But it does clearly identify the issues related to oil visocosity in general.

http://www.micapeak.com/info/oiled.html

And finally, a few people seem to think that because a particular oil gives them a higher oil pressure, it must be a good oil for their cars. That is simply not the case. Put straight 50-weight oil in the engine, and pressure will jump right to the limit of the pump relief spring.... really high.... but not very good for the engine. "High pressure" is not a sign of the correct oil.

 

Its accurate if you had two identical engines, side by side, ran at the same times, in the same places.

Other than that, its not.

Make some trips to a cabin or somewhere with really dusty dirt roads, and youll have a significant difference over your last analysis ... Or if you have one with considerably more traffic driving versus open road cruising ... You will see a difference. There are literally so many underlying variables that its hard to say on that level, that GC is significantly better than M1. Maybe its just lower detergent so its showing the oil as cleaner ... Maybe one oil filter has a lower multi-pass efficiency than another ... Or someone has run more miles on the oil than they should ... Its just too hard to have a controlled experiment. I run M1, but would consider GC for the car. I dont drive it in the winter and it sits in a warm garage, so for me I would personally stick with a 5W for cold start ... 30 weight suits the engine very well. I get nice OP and M1 is a great oil, when my pressure starts to drop, then I would consider maybe a 10W40 (As I dont think Mobil makes a 5W40) ... You cant go wrong with either brand really ... And on a stock motor this difference is so miniscule its not worth discussing. On a built motor, you will be told what oil to run in it from the builder based on the tolerances anyways so...

I mean, im not trying to be a dick, thats just how I see it. Feel free to voice opposing opinions as I am always up for an intelligent "arguement" expecially if you have good reasoning behind it.

 

Mobil has a 5w-40 Truck and SUV oil, I think they may be calling it a Turbo Diesel oil now, but from what I heard it was the same thing. I saw a 4 quart jug at Walmart the other day.

 

Interesting ... This could be a nice option for everyone who is compaining about low ( significantly, like less than 20 psi at hot idle) pressure. Theres alot more to correct oiling than the right pressure, but this could be worth it for some. One of the biggest factors people forget about in oil psi. is the filter. Certain filters could cause a change in pressure of up to 10 PSI.

In fact, my friend had a brand new fram tough guard or whatever the ones with the rubber on the bottom are fail on him and have his idle psi go to zero. He thought he blew the motor it sounded so bad. Changed the filter, and the oil ( Only about 2 weeks on it) and it idles just fine at a 30 psi idle ... This was on a 351W.

 

If you regularly run your car in the same overall environment most of the time, then oil analysis is really your only tool to see how the oil is doing, IMHO. There is no way to do a completely controlled test, so it's the best you can do. Just because you cannot control every variable, I see no reason to not use the analysis data.

 

A factor I haven't seen mentioned is the fact that a good percentage of LT1's have had the stock oil cooler removed. This might be skewing the data in reports of personal "experience" from one owner to the next about issues they may or may not be having with oil pressure. The guys who still have their factory oil cooler intact who're getting up there in miles might be seeing lower oil pressure simply because of it's questionable performance and reputation for becoming gunked up.

Not going to fan the fires of debate over which oil is "better" but for those who are experiencing low oil pressure, if your factory oil cooler is still intact you may want to rule THAT out as a probable cause before blaming the oil itself.

 

^ What he said, I never even ran my with the factory cooler. Since I bought the car totaled, I put a decent oil cooler on it before the front clip even went into place. I can say that I think this is the main reason for my significantly cooler (than most) operating temps. My car just cruising around is almost always down at the 1/4 way mark on the temp gauge. In stand still traffic, it still never creeps more than a needles width past the middle mark.

 

Mine won't even go past the 1/4 mark in the middle of the summer in south florida. Gotta love my becool radiator.

 

Wow ... They're a pretty expensive rad. though arent they? Just Curious.

 

Getting off topic a bit.

 

what effect would a mixture of oils have?

 

I've been running the 0W-30 Syntec for about 20,000mi now with K&N filters and did quite a bit of bracket racing last summer. It does not seem to burn any oil and the pressure is perfect (K&N filter gives you great pressure). I chose to run it after seeing test results from a board member from a long time ago--I believe his name was Patman or something like that. By the way, I now have almost 107,000 miles on the engine.

 

i run 20-50 here in florida and i have noticed the the 20-50 does not break down like the thin oils after alot of hard driving ..as for startup never had any problem with any noise from the motor ...its damn hot here in orlando florida ..ive tryed the thinner oils and they lose there slickness so fast ..i would have to change my oil every 1000 miles ..been there done that ..