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Oil changes

for a 2000 mustang with over 120k miles, how often should i change oil. also had a car once, that had about 120k, and after i changed the trans fluid, i had nothing but trouble from the trans. should i change it now?

What does the Ford Maintenance Schedule (likely contained in the Owner’s Manual) have to say about oil changes? I would recommend an interval of ~4,000-4,500 miles or every 5 months, whichever comes first, but you should do what Ford recommends, rather than what I or another person on this board might recommend.

As to the transmission, I am hoping that you have changed the transmission fluid previously. Transmission fluid should be changed every 30,000 miles or 3 years (whichever comes first), and that is a reality even if the mfr’s maintenance schedule does not list that procedure.

When trans fluid is not changed every 30k miles/3 years, transmission failure can take place any time after 90,000 miles, so if your previous car had its first fluid change at 120k, the trans problems were coincidental to the fluid change and those problems really resulted from a total lack of maintenance prior to 120k.

If the trans fluid in the Mustang has never been changed, then you should do so a.s.a.p. However, don’t expect this Hail Mary Pass to save the trans from failure. It may well fail in the near term, but once again, it will not be the fluid change that does it in. When you have the fluid changed, DO NOT have a flush done. Just have the trans pan dropped so that the sludge can be scooped out of the pan. Then have new fluid of the proper type and specification installed along with a new filter, and begin praying for the best.

When you changed the transmission fluid on your last vehicle, did you do a pan drop/drain and refill? Or did you have the all the transmission fluid exchanged?

Tester

had a car once, that had about 120k, and after i changed the trans fluid, i had nothing but trouble from the trans.

So why did you change the fluid at 120k.  Could you have detected some sort of problem or change that you thought might be a problem and changed to fluid in hopes that the new fluid would take care of it? 

Lots of people have done just that, then they blame the fluid change on the problems that follow.  In reality the change did not cause the problem, the problem was already there.  It was too late for a fluid change to fix anything.  Now if they would change the fluid say every 30 - 40,000 miles, they likely would not have had the problem at all.