Motul 8100 Oil
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Well I'm a ChE, that worked for many years for Mobil in the lab that developed Mobil 1, and I call BS on that. 1st, 30 and 40 designate a range of viscosities, not an exact viscosity, so it is quite possible for a heavy 30 weight and a thin 40 weight to be almost identical. 2nd, assuming your 40 weight is thicker than your 30 weight, the thicker oil will provide higher film strength and more wear resistance and the expense of higher pumping losses (lower HP and MPG). It's no big deal and you or your engine won't notice the difference. I wouldn't hesitate to use 40 weight, especially if I was tracking my car or driving very aggressively often.
Well I'm a ChE, that worked for many years for Mobil in the lab that developed Mobil 1, and I call BS on that. 1st, 30 and 40 designate a range of viscosities, not an exact viscosity, so it is quite possible for a heavy 30 weight and a thin 40 weight to be almost identical. 2nd, assuming your 40 weight is thicker than your 30 weight, the thicker oil will provide higher film strength and more wear resistance and the expense of higher pumping losses (lower HP and MPG). It's no big deal and you or your engine won't notice the difference. I wouldn't hesitate to use 40 weight, especially if I was tracking my car or driving very aggressively often.
And, to o0mikeyboy, it's your car and your warranty, so use whatever viscosity you want. But, if in the slim chance you'll end up in a fight with Nissan because you used a viscosity different than that specified, don't say we didn't tell you.
Florida G35 Club, Premier Member
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From: Orlando, FL
yep, i know. I think i'll take the chance.
Yes, I agree, one man's 30W is another man's 40W. But, we know that "thickness" isn't really viscosity. It's just easier to think in terms of "thickness" rather than "flowability". I think what my friend was really telling me was 1) if Nissan wanted 5W-40 in this engine, they would have specified 5W-40, and 2) if Nissan was ever looking for a way to deny warranty coverage on an oil related failure, the owner's use of something other than 5W-30 would be an out for Nissan. If 5W-30 works, why use 5W-40 or 0W-40 if you might end up in a fight with Nissan?
And, to o0mikeyboy, it's your car and your warranty, so use whatever viscosity you want. But, if in the slim chance you'll end up in a fight with Nissan because you used a viscosity different than that specified, don't say we didn't tell you.
And, to o0mikeyboy, it's your car and your warranty, so use whatever viscosity you want. But, if in the slim chance you'll end up in a fight with Nissan because you used a viscosity different than that specified, don't say we didn't tell you.
Everyone can do their own research and make up their own mind. If someone wants to follow the manufacturer's change interval and viscosity, like Road & Track which "complains" about it with the their long-term EX, because they feel more comfortable, well, maybe that's cheap insurance. Who's to tell them they're wrong, or even foolish?
Last edited by notalk; May 14, 2009 at 10:36 AM.
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