Synthetic gear / MT oil

What's the general consensus on synthetic vs traditional gear oil in the (manual) trans, t-case, and diffs on these trucks?

It seems there's mixed results. Some say synthetic (redline, amsoil) makes the shifting smoother and at least one person said it made it worse. I'm curious as the way mine shifts definitely leaves a bit to be desired. Also with the syncro probs of the last 6sp mt, I'm looking for preventative options.

I just remembered that I read a post today that said Toyota specifies a proprietary oil for the t case...first I'd heard that...

Anybody got a few K miles on synthetic with results to share? Trans, t case, diffs, any and all? Again, how many miles on the synthetic?

 

I use AmsOil in my engine, transmission, transfer case and differentials. Shifting was noticeably a bit easier after switching.

 

How many miles on the amsoil?

 

Redline MT90, best MT oil I've ever run.

Edit: assuming 3rd gens use 75w90 like 1st and 2nd gens do

 

Cool. How many miles?

 

I always change it out at the recommended interval (about every 30k), between my supercharger and the 4x4ing I do I like to keep it fresh. I'm sure it could last longer than that though. It's a popular choice here on the forums, I'm sure others will chime in about their experiences.

 

Amsoil throughout. Will be in my AT when it needs servicing.

 

I'm leaning toward the redline.

On a side note, I changed out my engine oil at 1k with Mobile 1 synthetic, but noticed it runs quieter with the Toyota stuff.

 

The Toyota syn is probably better than Mobil 1. Try amsoil signature next time. I think you'll like it.

 

About 20,000 and 3.5 years.

 

Why do you guys have a preference re: amsoil v redline? is there any data that shows one being superior? just curious...

 

Nice

 

Check out bobistheoilguy.com and you'll find all the info you could possibly ever want of automotive lubricants.

 

i'll check it out

 

There is a good amount of research from differential builders to suggest synthetic is not the way to go for diffs. It doesn't dissipate heat as well as traditional oil, and has been known to cause problems in diffs. At least one aftermarket diff company says synthetic oil voids their warranty.

 

Which company?

 

Ford XT-M5 is the best mt fluid you can buy

 

That actually sounds familiar, thanks

 

Are you running it?

 

Yup have been for about a year! Personally I wouldn't say any fluid will dramatically smooth out shifts. Also when I changed mine at 18k the stock fluid looked new still. It was slightly smoother than stock however.