re:Oil Stuff (long but worth it)

["Chris Brandt" <Chris.Brandt@xxxxxxxx>]

There is no difinitive best oil for all conditions but here are my 
thoughts/oppinions. I will qualify these by saying I am a mechanical 
engineer who has had the chance to study the properties of different oils 
in a lab type scenario.... First things first, it is well documented that 
90-95% of engine wear occurs on startup/warmup. SAE papers, field tests, 
tribology guys all agree. So anything that can be done to alleviate this 
is very good for engine life. But before everbody runs out and buys one of 
those pre-luber deals remember that a well maintained properly serviced 
engine will last a very very long time and then usually die from a 
condition other than an oil'd "wear" component type of failure. Exceptions 
exist but this is a general statement.

In the lab, synthetic oils would beat the dino oils in an oiled journal 
pressure test but the pressure levels were so ungodly high that it was in 
the area of plastic flow in the bearing material. If you get to these kind 
of pressures in a running engine you will be changing rods and cranks 
along with the oil.
The synthetic did really crush the dino oils at elevated temps. If you 
have a turbo run the synthetic...
The surprising results of synthetic vs. dino oil came from some cold start 
testing. We being young know it all types of engineering students decided 
we would look at the starting process in a bit more detail. This is in 
Saskatoon Saskatchewan, Canada in January ambient temps in the minus 40's 
( F or C when its that cold it just doesn't matter...) The steps are as 
follows: walk out to driveway, open door but do not get into vehicle (seat 
will crack...) reach down and give accelerator one pump with hand to set 
the CHOKE, start engine, make sure heater is on, close door, walk around 
front amd unplug block heater,  go back inside house, wait 20 minutes for 
interior to warm up. Now most of you wouldn't even dream of doing this to 
you /M whatever so don't flame me for that. The important points are as 
follows. The engine is "warm" because of the block heater, the choke is 
engaged because the air temps are way cold. The warm block keeps the oil 
warm enough to pump it is a bit warmer than an unplugged car at lets say 
50 degrees F, which all of you guys do. The oil is getting to the journals 
and doing its job. The problem is with the choke, (cold start injector..) 
synthetic oils have a very scary tendancy to breakdown very quickly when 
introduced to gasoline. Performance goes way below that of dino oils very 
quickly. This was 7 years ago or so using a very common synthetic oil so 
maybe there are some contemporary oils that don't do this.

So the cold start advantage of synthetics is ofset a bit by wetting the 
cylinders with gas. We worked with blending synthetic and dino oils with 
some pretty good results. I have seen guys shear of the drive pin to the 
oil pump by running the wrong viscosity and not being able to pump it

The other job of oil is to carry little pieces of metal, plastic, rubber, 
carbon, et.al.  away from the crankcase, and leave them in the filter. 
Obvious right.

Oil also plays a larger role in cooling an engine that most people even 
think about, right Porshe guys..

So we have oil doing three jobs, I could desertate on the order of 
importance of the three but suffice to say that take one away and the 
other two will not matter for very long. 

Here is my summary. Flame suit is on...

# 1 priority is to change the oil, often. Obscenly often. I rarely go over 
2500 miles on a change. My standard interval is 2000 miles. A simple 
2,4,6,8 progression on the odometer. This keeps the little wear bits out 
of the journals and doesn't let the cold start oil dilution become a 
factor. As far a s viscosity selection I use manufacturers recomentations 
for all but the last quart of oil. For the last quart I run a light 
synthetic. Pick your favourite. I have been playing around with syntec a 
bit lately because of its tendency to  be sticky on the cylinder walls. No 
results back yet. Viscosity selection is very dependent on internal 
clearances and required film thickness...Which the desing engineers know 
better than I do... This is for daily driving non turbo applications. Oil 
coolers on two, with an oil cooler/warmer on the 4X4 pickup (water to oil 
exchanger...works with mentioned block heater). I inherited vehicles with 
400K miles on them without the lower ends ever being touched. Learned the 
short interval thing from dad and grampa long before going to school. 
Grampa used the same stragety on a fleet of farm vehicles dating back to 
the 30's. Had tractors with over 20,000 hours on them still running 
strong.

And now for the truly scary part. I will take the used oil from my good 
cars (M5, 635, ...) and run it in my winter beater of choice (Wagoneer, 
Suburu..)..I don't start my /M car when its cold either !. Helps me 
justify the short interval expense.

Crazy, but you have to be to live in 40 below....

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