Gizmo54

I read in this forum about thinner oil. I have only had my 1999 rx300 for 2 months now. It was posted that a thinner oil would help, so I tried it. Our rx300 is running cooler and quiter now. Our mpg has increased by 2 mpg than what it was before.

Lexmex

Welcome to the Club.

What brand and weight of oil is it?

hypervish

Welcome to Club Lexus!

I have hard time justifying a 2 mpg increase just by changing to a lighter weight oil. Have you changed your driving habits?

It is true that a lighter oil can improve fuel economy, but 2 mpg just sounds like a lot.

And, running quieter could be a placebo effect. What do you mean by running cooler?

BTW: I don't mean to question your honesty, I'm just trying to find out more by asking questions.

Gizmo54

I went to the Mobil 1 site and read for about two hours on all of their info. Again let us remind you that this was the first time we had changed the oil. We are not sure what oil was in it at that time. We also put a K & N air filter in even though the one in it looked new.
I have hard time justifying a 2 mpg increase just by changing to a lighter weight oil. Have you changed your driving habits?

It is true that a lighter oil can improve fuel economy, but 2 mpg just sounds like a lot.

And, running quieter could be a placebo effect. What do you mean by running cooler?

BTW: I don't mean to question your honesty, I'm just trying to find out more by asking questions.[/QUOTE]

hypervish

Be careful using a K&N Filter. If you oil it too much, the oil will end up on your MAF sensor and set a CEL.

lexus114

Yup, what my pal said ^^^^^^^ only oil the side that gets the dirt. BTW, re; the thinner oil. I ran Pennzoil Platinum 5W-20 earlier this year, and I could not believe the difference! It had more pep, and better gas millage. But, it had a bad thump in the drive train at low speed going in to a certain gear. (after letting off the gas, and giving it gas again) It`s like the added cushion of oil was not there. Plus my valve`s were kinda noisy as well. I have to admit though, I may put it in again. Oh, and the vvt-i didnt seem to kick in on the 20 weight oil either. But everything else the op mentioned, I can assure you is true.

hypervish

How much of an mpg gain did you get?

I may have to give it a shot. I just did an oil change though with PU 5W-30.

BTW: you buy a new Benz?

lexus114

Well # 1 about 2mpg`s highway, and approx. 1mpg city.

# 2 yes........

hypervish

Wow, 2mpg on the highway. I never would have thought an oil could improve mpg by that much. I think I may try it out on my next oil change.

Now, it's time to treat yourself to another car as well. Maybe a weekend toy.

hypervish

It seems as though 2 mpg extra is possible. Thanks for bringing this up.

lexus114

The only reason I know about the 2mpg increase, is because we go to Bedford,PA at least once a year. And the last run was with the 5W-20 oil in the sump. I couldnt believe it either! But it actually got it. Oh, and it pulled the hill`s in Western PA much better too.

kalali

Not sure if 1-2 mpg gain/loss is much to get so excited about. First of all its within the measurement accuracy and secondly I can do much better than that by just a slight change in driving style. I'm willing to bet between the ethanol content and/or ambient temperature variation has more effect on gas mileage.

hypervish

I can do much better as well by changing my driving style, I can beat the EPA rating without even trying. But the point of this was to emphasize the fact that a thinner oil improved mpg by 2 miles.

Of course ethanol is the biggest variation on gas mileage. There is 10% ethanol in pretty much every gas station, unless you find one from pure-gas.org.