I went to socal for the labor day weekend and i was getting 25.5 mpg on my car with AC the whole time. i wasnt on cruise control or anything and i had frequent stops too. I was surprised!! BTW I have a 98 gs4 with 110k miles on it. What i did was i switched to fully synthetic oil and i changed the tranny oil everytime i do a oil change. Tranny oil only cost 10 bucks, 5 bucks a quart. I figured since gas prices are high, the only way to save is to keep the motor and tranny run more smooth. Even for local and freeway driving, i get average of 22mpg with ac too. Before i did the switch, i was getting average of 18mpg. Do the math and you know you save money, in addtion, synthetic oil makes your car last longer.

the gs4 tranny only takes 2 quarts??? I'd stay with the synthetic oil , but honestly id only do the trans fluid at the earliest every 3rd oil change..

I drive like a grandma.

Do you use synthetic tranny fluid too?

What tranny oil would you reccomend?

Word. Thats how i drive great gas mileage.

The oil and tranny fluid change is not likely making that dramatic a difference in your mileage, nor is switching to synthetic. I very highly suspect that the difference is that wherever you are getting the oil change done is inflating your tires for you! Ask them next time you go in if they do it


Member Mmarshall started a good thread on how to save gas with some excellent tips
https://www.clublexus.com/forums/sho...d.php?t=177157

Good point! Most of the time I overlook the obvious.

Amsoil Universal. DaveGS4 Uses it It is full synthetic and compatible with our trannys. I'm going to put that in soon.

MOBIL 1 all the way for me

I have used AMSOIL Synthetic fluid as well for the last 2 years, and could not be pleased more. The fluid stays cleaner and handles normal transmission heat much better than Toyota TYPE T-IV.

I believe the worroes about transmission failures if you deviate from stock are unfounded, although people can choose what they like if it makes you feel more secure.

NUFF SAID!