Autocross/Hillclimb Oil Article
 

I read both articles at this link, but the one in the sidebar is far more insightful the other.

So...If I was looking at doing a hillclimb this summer out by Arcada, Id be ok with my 5W-30 right?

IMHO, pretty much any situation except driving at the track in hot weather or towing something heavy, 5W-30 is fine, especially if it's a quality full synthetic.

Remember, the lower number is the weight that the oil acts like when it's cold and the higher number is what it acts like when it's hot. These qualities allow an oil to maintain the proper viscosity in a range of conditions.

I just bought some Rotella T 5W-40. The 5 means that the oil will be thin enough to circulate when cold, just as thin as the manufacturer intended. However, the 40 means that it will maintain composure (film strength, viscosity, etc) better when hot.

The fact that it's a great synthetic (gets great UOA's/reviews in Subaru's) is the main reason I bought it though. And it's $5/quart at the Pepboys where I buy my Purolator Pure1 Oil Filters.

That's my thinking anyway. Hopefully I'm not wrong. I was just reading the back of the jug and it says it's "suitable for" tractors, pickups and big rigs.

I just reread the article and it's wrong.

pretty much directly contradicts

http://auto.howstuffworks.com/fuel-e...estion1641.htm

I guess I should have read your other post more carefully. Oil weight is written like "5W-30", which I learned to think of like "5 Winter (the cold viscosity) dash 30 (the hot viscosity)".

But the article is still correct in that 20W oil is going to be bad for a motor that expects 5W or 0W when it's cold. Like they said, racers tend to use heavier oil to fight the viscosity breakdown that happens when you over temp the oil. Since that's not happening at autocross, there's no gain for using the thicker oil.

I think your logic for the 5W-40 makes sense. 5W is going to be close to (exactly?) the factory recommended cold weight, while the 40 should afford a little extra protection on hot days when running hard, at a small expense of fuel mileage and horsepower. I just wouldn't bother with using non-factory recommended oil weights unless you are in fact running the car hard in the hot. 5W-40 probably won't make a huge difference, but running 15W-50 or something in a street car that never really gets super hot oil temps is probably going to accelerate wear on the motor over the 0W-30/5W-30 factory spec oil.

Agreed.

I tend to use a thicker oil when my car eats it non stop. While will hurt the engine more in cold operation, but perhaps also help it out in cases where running 1-2 quarts low is harmful , the thicker stuff just doesn't get eaten as fast. (not sure if turbo seal or ring landing, could be a valve issue i guess too)

I had the same problem too...kind of. My old n/a engine wouldn't puke smoke until I hit the gas after letting it basically idle downhill for a minute. Boy, I could smoke up w whole intersection so bad that people could have thought it was a diesel in front of them. If that sounds like what yours is doing, here's your problem...bad valve guide seal.

Um, your engine didn't have a bad valve guide seal actually. ;) From what I could tell, all the ring gaps on the #4 pistons had managed to align themselves. There was no scoring or damage to the cylinder or the piston when I tore it down, and replacing all of the valve guides hadn't solved the problem.

Clearly the problem is ghosts.

FIxed

I still run the Rotella T6 and have even stopped switching to German Castrol for the Winter and just run the T6 year round. I feel like my car loves it and it's cheaper than GC. The T6 has slowly been crawling up in price at least at PepBoys which I buy it at since they have my favorite oil filter and using my Discover cashback to buy a $25 Pepboys gift card for $20 offsets it.

But the reason I'm bumping this thread is that I just found the 4qt jugs of Rotella T6 at the Walmart by The GSR for around $21.50/gallon jug. Not sure if this is something new or not, but there you go.

How much oil do you burn between changes?

I burn about 1 quart every 2K miles. The Royal Purple burned more quickly probably due to it's tendency to shear to a lighter weight toward the latter half of the OCI. I'm nearing the 150K mile mark. I could never tell a difference between the GC and the Rotella. I think I burned less of the GC, but that's probably because I ran it mainly in the Winter when I'm not racing.

Been this price for at least the last few months. I plan on switching to T6 as soon as my remaining stock is used up.