Got my oil changed for the second time on the car (got the car used at 11700mi. and now at 19k). I used the coupon from the dealer the first time but stupidly didnt ask what kind of oil they used, I imagine they used the cheapest 5w40 they had...

This time, I had them put in Mobil 1 0w40 and there was a huge difference right from the start. The car seemed much smoother and even.

Am I imaging this or have others had a similar experience?

(08' g37S)

 

I always thought the official oil weight was 5w30, so they probably tossed in cheap 5w30.

If it was 0w40 AFE, let me know your impressions and any measurable changes in performance.

Thanks!

 

You're imagining it.

 

dude your head is playing tricks with you.
the only real advantage to that weight oil is quick cold-weather starting and ultra-fast protection due to being so sheer/thin.
I would not run that light of an oil in the spring/summer.

 

M1 0w30 AFE actually has higher 40c/100c viscosity than 5w30 PP or PU. M1 0w40 is even higher, so it shouldn't be an issue.

 

As above, the viscosity of the oil increases with higher temp to give more protection (as i understand it). It'll help with start up in the cold but will still provide good protection as the engine heats up or if its hot outside to begin with...

And yes, it may be all in my head =). I'll follow-up if I have any gas mileage or performance benefits...

 

i still feel its to thin for the initial start-up of the engine in warm months, which as we know is the worst few seconds for an engine.

 

I respect your opinion on this one. I usually ask people about their experiences, so that I can evaluate their choice without taking the risk myself. I usually stick to whatever weight is in the manual.

I had been considering switching to Mobil 1 AFE, as it touts improved fuel economy. However, the wording they use implies that this is achieve by having a lower viscosity. Thanks to this thread, I looked up all the viscosities and found that the PU/PP viscosity is lower over much of the temperature range. The difference in pour points and very low temp viscosity doesn't strike me as too huge. In addition, any temperature below freezing in Texas is considered too cold. Right now, the big jugs of PU/PP from Walmart seem to be in the value sweet spot.

 

You want thin oil at initial startup since thin oil flows better than thick oil. Even in warm months, having too thick of an oil will not flow as good as thin oil on those first few seconds when the engine is cold. That's what multi grade oil is all about. It has the high flow properties of low viscosity oil to aid flow when the engine is cold, and the higher viscosity breakdown resistance properties when it gets hot.

 

That, my friend was well said, and you are absolutely correct!

 

yes in the cold weather. temps when its near or below freezing.
when oil moves like syrup.
but you certainly dont want the same viscosity when its 90+ degrees out.

-there is a reason our cars are rated for the oil they are. thousands of dollars was spent on research to choose an oil that will serve our engine appropriately. the only time i would modify which oil, is in extreme temps/service.

 

ive lived in CA my whole life and ive learned not to **** with the second number (viscosity, right?) i've always though our oil was 5w30