correct trans oil 4 speed

[rdssdi]

I just filled my transmission with Red Line MTL GL-4. It did not have a viscosity rating on the front label but the rear label said it replaced 60, 70 and 80 weight oils. I was uncertain if it was the correct lubricant for my Elan +2 (Cortina) 4 speed gearbox. It was on my shop shelf and I thought it had been purchased for the Lotus. Possibly I got the wrong product or I had a incorrect recommendation.

I called Red Line and they said while it will work with my transmission it is not what they would recommend. Apparently the original specification calls for an "EP" or extreme pressure lubricant which is not what I used. They said that their 75W90 NS was the correct lubricant. It is a GL-5 oil and I questioned if that was correct with brass syncros as I understood that a GL-5 oil would cause the brass to corrode. The Red Line tech person says they have an additive to prevent that in this GL-5 oil.


I purchased two quarts of Red Line 75W90 NS to replace the "MTL" GL-4 currently in the transmission. More work! Great!

If anyone has any advice to share I would appreciate hearing from you.

Thanks

Bob

[rgh0]

I don't know who you talked to at Redline but I don't think he was much of a tech person and needs to read their own literature on their web site and study a bit of lubrication theory and history.

The Redline MTL is the right lubricant based on their own literature and based on 20 years of extremely successful use by myself and others.

The EP reference is not relevant today and all modern GL-4 oils are far better than any 1960 EP gear oil and redline MTL is better than the rest of the modern GL-4 oils and it is specifically designed for a manual gearbox such as the Ford one. Gl-5 oils are only required for the hypoid gears in the diff and are not required for the helical gears in a Ford gearbox. The GL-4 rated MTL is far better from both a corrosion perspective and synchronizer performance perspective .than the Redline GL-5 rated gear oils.

regards
Rohan

[rdssdi]

Thank you for that answer.

Looking at the Red Line Oil web site they offer three GL-4 transmission gear oils.

MT-90 75W90
MT-85 75W85
MTL 70W80

I used the MTL 70W80. The factory manual calls for an 80 weight oil. So I assume that was the correct choice.

I have two quarts of the GL-5 scheduled for delivery tomorrow. Another shelf decorator. I just went out to the shop and found a partial bottle of the ordered 75W90 NS GL-5 oil. That must be what was in the transmission. That recommendation must have been given to me years ago as it was the other day. I assume since I also had two unopened MTL bottles I was planning on switching. My memory is terrible but that seems to be the series of events.


It is possible that when I told the tech that it was for a Ford Cortina transmission he assumed that was the same as a modern Ford manual transmission therefore the 75W90 NS recommendation.

I will keep the MTL in the transmission and feel confident it is the correct choice. Again, thank you for your advice and counsel. Now what to do about my memory.

Bob

[elanner]

I don't know for sure what was in my gearbox when I purchased my Elan a couple of years ago, but the seller told me it was Castrol Hypoy C 80 and I have no reason to doubt him. It seemed to work fine and I thought the gear change was pretty good. I didn't touch it for a year, until I finally got around to changing it. I switched to RedLine MTL 70W80 GL4 following advice in this forum and I have to say that the gear change has definitely improved. While it's noticeable all the time, the most clear evidence is how much easier it is to select first from a standstill. Any baulking has essentially disappeared.

Nick