After reading a little about oil weights on the internet, I decided to move to a heavier oil.

This past weekend I put in a fresh 4 n quarter quarts of 20W-50 Castrol gtx regular oil.

In the middle of this week, we took a trip to Charlotte, NC and I was not happy with gas mileage. It went down from the 29.2-30.7 to just 27.3-28.1.

Coming back to Jax this morning I switched back to the 5W-30 Castrol GTX regular. I just drove about 50-60 miles and I noticed I am back to 31.3

Question... So how does the difference in oil weight really affect the VQ. I frankly thought the 20W-50 would work so much better in the 92+ degree FL weather but now I think I'm going back to the lighter oil.

 

http://forums.maxima.org/forumdispla...sprune=30&f=70
http://forums.maxima.org/showthread.php?t=227996

 

I think time to move post to another forum....

I did check those links... but there are hardly any threads on 20w-50

 

The manual recommends 5W-30 for better fuel effeciency. I think almost every manufacturer recommends it.

 

Here in South Florida, I've been using 15W-40 in the summer and 10W-30 or 10W-40 in the winter.

 

The ring and bearing clearance of motors can be so exact that even a switch to a heavier weight oil can cause driveability and economy problems. And wtf are you doing with 20W-50, thats insane and stupid. Dont believe everything you read on the internet, that or have someone that actually understands what their reading translate it to you.

 

errr....ummmm...... a lot of you guys need to go to school in auto mechanic or in petroleum study, the W does not mean weight, the W is as in winter. If you guys don't know that, prove me wrong, cuz I know this well. it not weight it has to do with the veloscity of the oil.

 

use 5W-30 or 10W-30 Mobil 1...car runs great...

 

everyone, please ignore these links.

what ype of oil does everyone use?

 

WTF? Im thinking he means viscosity but whatever.

Just keep running 5w30 or 10w30 as everyone else says. Your mpg went down b/c of more friction.

 

true.......use what is recommended...

 

Wow... how to respond to something so stupid. Really? Cuz you know this well? Just cut your head off dumba$$.

 

I'm is the rinse phase of ARx with Valvoline dino 10w30 and I am getting about 2-3 mpg better than I get with GC this time of the year. GC is not "Energy Conserving". I know the ARx may be helping a little, but IMO the real difference was the energy conserving rating of the valvoline oil. The last two tanks have yielded 28.5 mpg (60/40 hwy/city) and 27.8 mpg (40/60 hwy/city). With GC I was getting 25-26 mpg at best. I cannot imagine what a 17-18 cSt oil may do to gas mileage.

IMO, if mileage is what you want, you have to use an "energy conserving" oil, but that's still going to be a xW30 oil.

 

My choice is 5w-30 castrol.

 

im running 10w 30 and doing about 80hgwy 20 city and, i dont get no 28-30 mpgs. im only getting about 24 and i dont run it hard

 

Clearances and oil pump aren't going to like that thick of oil. The manufacturer wouldn't tell you to run a 30 weight oil if it wasn't tested thoroughly. When I had my Max, I was averaging 22mpg rush hour and between 32-34hwy depending on how fast I was driving. That was with Amsoil 0w30.