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cody · 2010-04-04, 08:58 PM

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.

2010-04-04, 08:58 PM	#3
cody Candy Mountain Real Name: Cody Join Date: May 2005 Location: Californication Posts: 7,751 Car: 03 Pussy Wagon, now with more pink! Class: TESP OMG Internet!	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. __________________ Slow and low, that is the tempo. Last edited by cody; 2010-04-04 at 09:00 PM.