Hello,
Recently purchased a1989 F150 from an older couple. As they didn't drive it often, it only has 35k miles on it.
Saw a recent video by Scotty about being careful of changing the transmission fluid in older high mileage vehicles.
Shifting is smooth no issues there but I'm thinking about changing the fluid in the manual transmission due to its age.
Question: Is this a good idea?
If so what's the best fluid for an older truck like mine. I believe it has Mercon ATF currently.
Thanks,
Jack from Tennessee
Since it is a manual transmission I would change the fluid. Oils can break down with age and most manufacturers recommend changing manual transmission fluids every 30,000-60,000 miles. This is because if there is any debris in the fluid it can wear the synchronizers and bearings excessively.
On what Jacksonishere said, I have heard of some mechanics not changing the fluid in Automatic transmission due to the fear of causing leaks or slipping. But since it is a manual it is not much different than changing the oil in your engine. (other than longer service intervals)
@_aragorn_7
What manual transmission fluid is best in your opinion?
If you are willing to spend the money, Amsoil is the best. Otherwise I use Castrol Transmax Dex/merc.
https://www.amazon.com/Castrol-03520C-TRANSMAX-MERC-Gallon/dp/B00DILUBL6
@_aragorn_7
No kidding Amsoil is proud of their products. They want around $16.00 per quart.
NO NO NO NO This a horrible idea. The only time you change the fluid is if the car is less than 100k miles and less than atleast somewhat new car. This thing is way to old and your just asking for problems if you change it now.
@jacksonishere
It's only got around 35k miles on it. I was thinking it would be okay. If it was higher mileage I'd probably hold off. You think that the age of the truck is the issue?
This is a manual and not an automatic. Yes changing the fluid is a good idea. I have had this transmission and I have had much experience with it and driving it. Newer ATF fluid is better than the stuff 20 or 30 years ago and this will help greatly.
The drain plug is on the bottom of the trans and there is a fill plug in the side. You can also fill this trans from the top by removing the shift boot and unbolting the gear shift from the top of the trans and just pour it in. Don't fill the trans much above the drain plug. Keep it right at the drain plug level. You can see it with the top of the trans open.
These transmissions are robust but there is not many of them left. If you break it there are very few replacements. Drive it with care and be easy with it. It will give you YEARS of good service. The 300 inline 6 is a fairly bullet proof engine. Also it gets MUCH better gas milage with the EGR valve eliminated. You can also run a glass pack in the exhaust with minimal noise. Its a very quiet engine. I used to get high 20's for fuel milage with mine. Good luck
@autoelectrical
I've heard good things about the 4.9. Some folks think ford made a mistake getting away from it.
Any particular manual transmission fluid you think I should run?
I didn't pay much for this old truck but that doesn't mean I don't want to take care of it. I figured it would make a solid work truck or as Scotty would call it a good knock around truck.
Find out what Ford put in it and replace it with the same only synthetic. Clean off the drain plug as these are usually magnetic and collect metal fragments.
Castrol Purple Power Valvoline are all excellent oils.
NOTE -- Some manual transmissions use ATF fluid. Find a synthetic version of the recommended type and use that.
Yes I would change the manual transmission fluid. Automatic NO.
