Oil weight and gas mileage

[tiredoffixing]

Can oil weight affect gas mileage?

[psycoreefer]

yeah, at least a little bit. I've heard thats part of the reason all the auto manufacturers are now recommending 5w30 or 0w30 in new cars instead of 10w30 like they used to.

[powerram50]

heck ford is big on 5w20

[XSPastor]

The nascar dudes put a very light weight oil in to qualify. Light weight oil, less drag; less drag, better mileage. (and top speed) For the rest of us though I think it would be splitting hairs. I can't imagine any substantive improvement in gas mileage that would warrant the extra risk to the engine's longevity.

[tiredoffixing]

Reason im asking is i was runing 15w40 and went to a 20w50 and i went from about 30 down to 24 I am thinking of going to synthetic

[XSPastor]

I'm having a hard time believing that oil would make 6 mpg of a difference - but then I've never tried it either. Interesting.

[tiredoffixing]

oil

Thats all I did was change the oil

[tiredoffixing]

Thats al I did was change the oil

[egsols]

I'm no expert but synthetic might cause problems with your clutch.

I recently, by accident, put 5w20 in mine. I realized my mistake when all the mosquitos started to die off.

BTW I used to run Rotella 15W40 in my other 79, now I'm running Castrol 20W50 on my new 79. The new 79 does get way better mileage than the old but that could be due to having the carbs set up better. Not really sure.

[mitch]

Oil

Im not running an XS any more but i do run Amsiol motorcycle oil i found it shifts smother runs cooler , last longer and no probs with the clutch but thats just what i have found. your results may vary!I now change my oil every 6000 miles and the oil looks as clean as when i changed it. but its very expensive at 10 dollars a liter.
Doug

[tiredoffixing]

Amsoil states that it is wet clutch compatable. Does anyone here had any luck with it?

[tiredoffixing]

Thanks for your help

[TopCatGr58]

Hey Tired,

I remember reading about a few folks who went from 10-40 to 20-50 and they started to experience clutch slippage! I don't recall if it was Synth or Dino based, but the thicker oils are a bit more slippery, and even though you might not be able to sense any rpm rise at a certain MPH, but it could be slipping a little. The 20-50 range means that it's supposed be able to have the thinness of 20 weight , especially in cold weather, but has the breakdown resistance of the 50 weight!! So..I wouldn't think that it's causing too much resistance with the crank sloshing thru the pan!

Haven't used Amsoil, but have heard good things about it, but ANY oil has the potential for aggravating a marginal grabbing clutch!?
T.C.

[Paintman]

Amsoil

i use Amsoil 20W50 syn in mine and have no problems with the clutch even dropped the head temp when idiling.

John

PS dont want to start another Oil war LOL

[Crazcnuk]

Try a 3/4 conventional oil, 1/4 sythetic oil mix. You should see an improvement over straight conventional AND straight synthetic.