Fancy Synthetic oil for transmission, worth it?

[LR Max]

I've got a 1973 Land Rover 109. At higher speeds I've got a high pitched wine. The transmission has decent components in it and I'm due for an oil change.

I'm considering putting in fancy Amsoil or Redline transmission fluid in as well as the transfer case. I ask others with older transmissions, is it worth it? Notice a drop in temp, sound, and driveability? Their websites claim all kinds of things but wanted to find out if anyone had any experience with these in older truck manual transmissions.

Thanks for any help!

 

[1911]

Personally I'm sold on the benefits of synthetic lubes and use them whenever possible. I buy Amsoil Severe Gear lube in 5-gallon buckets and use it in every manual gear box and differential that I own. When I put it in my 1980 FJ40 Land Cruiser manual gear box, it got much quieter with markedly less gear whine. Runs cooler too.

 

[Tappet]

Although benefits with Synthetic oil are there. Be a little wary.
I picked up an old Isuzu 4X4 some years back. It's previous life was not the kindest. So I thought lets put in some wizzy Synthetic oil. Transmission was quieter and did run cooler, however a few weeks later the rear seal started leaking and then the seal between the Transfer case and Gearbox started leaking.

After talking to a very experienced mechanic, he said it's not the first time he has heard of this. The synthetic oil can wash away the crud that has built up on the seals over the years and before long they can leak.

 

[65 scout]

Although benefits with Synthetic oil are there. Be a little wary.
I picked up an old Isuzu 4X4 some years back. It's previous life was not the kindest. So I thought lets put in some wizzy Synthetic oil. Transmission was quieter and did run cooler, however a few weeks later the rear seal started leaking and then the seal between the Transfer case and Gearbox started leaking.

After talking to a very experienced mechanic, he said it's not the first time he has heard of this. The synthetic oil can wash away the crud that has built up on the seals over the years and before long they can leak.

The leak issue is dead on. Very common. Doesn't happen to all but many. To me the real benefit of synthetic is it's ability to take the heat. Unless your running into excessive heat issues I just don't see an advantage. A friend of mine a few years back was a mechanic at a Ford dealership when Ford started using synthetics in the drive train on Super Duty trucks. They had an exceptional amount of rear diff failures that Ford attributed to the synthetic gear oil. He stated that the synthetic oil would draw excessive moisture. Just food for thought.

 

[LR Max]

Thanks for all of the input. My seals are fairly new so I'm not too worried about that.

Currently looking at Amsoil and Redline. Currently talking to peoples that deal and going to see what they can do for me.

 

[Kaisen]

They do make seal conditioners to address the leaking

Redline is a fantastic product. Not as impressed with Amsoil, but many swear by it.

 

[LR Max]

Thanks for the feedback. Which Redline product did you use? What made it better than the Amsoil?

 

[Kaisen]

Thanks for the feedback. Which Redline product did you use? What made it better than the Amsoil?

http://www.redlineoil.com/product.aspx?pid=45&pcid=7

I've used MTL in manual transmissions for almost 20 years

 

[Kaisen]

I've always used OEM ATF. Changing the fluid according to the service schedule and using a transmission fluid cooler has worked well for me. However, Amsoil is my go to fluid for differentials and the transfer case.

He's asking about a manual transmission

 

[Inyo_man]

He's asking about a manual transmission

My bad...

 

[evilfij]

On a lotus, yes, on a land rover series, no.

 

[huntsonora]

Make sure you get the correct oil for your manual transmission. I bought a little toyota truck as a hunting vehicle last year and when I got it it had a little difficulty going in to 3rd gear. I knew that it required GL-4 oil but thats not that readily available so when my Amsoil shipment arrived I drained and filled the transmission with the GL-4 oil and it now shifts like butter. Most oils on the shelves are GL-4/GL-5 rated and that doesn't work with my transmission

Amsoil is an amazing product as is Redline. I would go with whichever one is less expensive and easier to get

 

[FordGuy1]

Sweptco makes some great products. Have used many different brands of lubricants in our race truck and for trans Manuel,auto, or power steering there fluid it great.

 

[LR Max]

Thanks for all of the info.

My truck needs GL-4, for sure. I found a local guy who can get me some Red Line MTL oil for a reasonable price. Gonna go that route and see if it makes a difference. If it does, hooray. If not, then back to Autozone tub oil for me.

 

[evilfij]

Max, I would use redline MT90 over MTL. MTL is way too thin for a series box.