Fritz, I lost about a mile to the gallon by going to Mobil 1 5W-30. I check my mileage religiously so I'm not just guessing at MPG, I really did lose a little. My next oil change I'm going to 5W-20 again. I wish Mobil 1 would make some, but until they do, I'm gonna have to switch.

 

I am curious as to what kind of MPG you are getting. I usually get between 12.4 and 12.8 MPG with a little around town driving.

 

I use 5w-30, like my book says. I use petroleum based oil now, but will be switching to Mobil 1 synthetic on the next oil change.

 

So it sounds like if i go from 10w-30 to 5w-30 it wont screw anything up.

FRITZ, Silver Stock 2001 "L" BaBolt's s/s tips

 

01lightning, I average 14mpg city/15mpg highway. Used to be 15/16.

 

Lets say we didnt care about gas mileage. Whats the difference between 5/30 synthetic & 5/20 synthetic. Not the scientific difference, I mean in a stock lightning, what are the pros/cons of the different weights? I mean is one better for horsepower/cooling/wear/acceleration? I have 900 miles on my L and am going to Valvoline soon to change to synthetic. What are the benefits of the two different weights? What are the differences as proposed to the car itself? Thanx guys.
Gavin

 

macgregor45, how do you get such good mileage? Do you drive your L like a granny?

 

ttt

 

You should have no oil-related problems because you go from 10W30 ti 5W30. I run Royal Purple #11 Racing synthetic oil which is their 5W20 viscosity. 24,300 miles and still .

Dan

 

01lighting, you're not the first to accuse me of that!

I do drive it pretty soft when commuting, but I do lean on it time to time when the opportunity arises. Pesky R/T's, Vette's, etc...

 

Valvoline doesn't MAKE a SYN 5 W 20 yet ... FYI ...

 

fwiw - I just want to add a data point to this thread. I did my first oil change today: 2 months, 1428 miles, used 5.7qt Motorcraft 5W-20 'Premium Semi-synthetic', Motorcraft FL820S filter, prefilled filter, cranked engine 3 seconds with throttle floored (to prepump oil), then started engine and let it idle for 2 minutes.

No marbles or any unusual noises whatsoever. In fact, it actually seems to be a tiny bit quieter now. I took it out for a bit, then did some WOT runs up to 80. Pulled back into the garage and let it idle for another minute.

Purrs like a kitten.