terahertz

hey i have searched around for an answer but have found none. People say to change around 10k to 15k miles, but my car is not driven very often while i'm at school so i guess im worried about the time aspect rather than milage. The LE607 is full synthetic i believe, so it should be good for at least a year. the GMSMFM is "semi-synthetic," so does anybody have a recommended interval for that?

thanks in advance.
i'm just trying to decide whether or not i will change fluids after schools out. i put both fluids in my car in december.

Ludedude

LE 607 is not synthetic at all. It's refined from dino oils.

terahertz

so anyone have a recommended interval for both then?? lol

thetz99

Heat and pressure degrade the oils not time...that's why the bottles on the shelf don't have an expiration date on them. If your's is a garage queen, just keep track of the mileage between changes and change them when prudent.

vtec9

tranny and diff oil will last a long time. the 10-15k mileage marker is for the 1st change to get rid of particles left after break in, this is not an interval for future changes. Once you hit 10-15k, change them both, then you'll be good for a long time

xviper

The tranny fluid should be good for 2, 3, 4 or more years, depending upon what you have in there and how you drive. With GMSM-FM, it has been noted that this fluid doesn't last long at all, in some cases, only after one track event. The tranny has the added advantage of having a small pump to circulate the fluid. It "can" last a very long time but not necessarily so.
The rear fluid, however, is a whole other story. This fluid should be changed within the first few thousand miles of the car's life and then annually or 10k to 15K miles thereafter, more often if the car is tracked or driven hard. We have a very tiny rear diff for what it is asked to do. Additionally, we have a very small volume of fluid for what it is asked to do. Too frequent diff fluid maintenance is never a bad thing. At the very least, do it annually till you can get a good "read" on what the old fluid looks like as well as what is stuck on the magnet. These will tell you volumes on the health of your diff and the interval which you should be changing fluid.

terahertz

okay thanks you guys. i guess i'll wait off until december to change the diff. i originally changed to le607 after around 5k miles last dec. the tranny i guess i will wait until i start to notice a deterioration in performance. i was just worried it would start to break down like engine oil does.

Wisconsin S2k

[QUOTE=thetz99,May 24 2006, 01:31 AM] Heat and pressure degrade the oils not time...that's why the bottles on the shelf don't have an expiration date on them.