Transmission / Overdrive: 3 speed w/OD

[Bo Markham]

Anybody? What is the current recommended gear oil for 3 spd. and OD unit?

I think Mobile 1 racing oil is the current recommended motor oil? Right?

[JoeHall]

Hi Bo,
For about 10 years I have been using Red Line MT90, specifically formulated for old stuff, including gearboxes with bronze synchronizers. Ted Harbit mentioned it on here, so I tried it, and have never looked back. I especially like that it shifts easily when cold.

[wdills]

I have been running NAPA GL1 90W mineral oil. This is what the stude service manual calls for. No idea how shift performance is compared to the more modern stuff out there.

[62champ]

Bo - I have had a lot of luck with Royal Purples transmission gear oil (full synthetic and plays nice with white metals) - and as Joe mentioned, it makes a heck of a difference with being able to shift when it gets colder. In PA, before switching, I really couldn't drive the blue Champ until it had sat and idled for 10 minutes or so.

[Bud]

I've been using Amsoil 75W-90 manual transmission lube in standard transmissions with good results. The GL1 SAE90 is old technology. While it will work, time marches on and better lubes have been developed which work much better especially in colder weather. Bud

[DieselJim]

I had a T85od in my 54. I ran SIN50 in it. It was good enough for big trucks with 600 hp engines. Fuller would warranty their trans 750,000 miles. Good enough for my Stude. SAE 50 has the same velocity as 90w mineral oil.

[StudeRich]

No the "preferred" here, Engine Oil is VALVOLINE Racing Oil, in the Silver bottle, standard Dino Oil 10W-30 or 20W-50.

Mobil 1 is a Synthetic.

Ask 10 people here and you will get 8 answers! There are Hundreds of posts here about ZDDP in Oils or additives for Flat Tappet Cam Engines without Roller Lifters or Overhead Cams.

[SN-60]

And here's answer # seven......Straight 30W Non-detergent oil!

[StudeRich]

Anybody? What is the current recommended gear oil for 3 spd. and OD unit?

I think Mobile 1 racing oil is the current recommended motor oil? Right?

Engine Oil was question Number Two! Question Number 1 had more than been covered when I showed up.

[kxet]

Napa GL 1 90 wt Mineral oil. Never hypoid or differential oil. I have lunched ODs with 50 wt. engine oil and the 90 wtsold in gas station lube pumps.Something to do with sprag clutch or brass/bronze parts. Several opinions on that. When I was having problems OD parts were in about every wrecking yard, now where do you find them? Be safe. Have a nice day.

[JoeHall]

For the Stude motor, Mobil 1, 15W50 has been working for me year round, since the late 1990s, and several hundred thousand miles. Never a problem and the motor stays clean as a pin inside. The oil does not even begin to darken on the dipstick till around 5000 miles, but with dino oil it is black as tar by 5000 miles. Though the gold cap stuff says its good for at least 15,000 miles, I change the Stude oil and filter every 10,000 miles with Mobil 1.

I realize most folks here will never even drive their Studes 10,000 miles, or even 5000, but just saying what Mobil 1 is capable of.

[Bo Markham]

Anybody? What is the current recommended gear oil for 3 spd. and OD unit?

I think Mobile 1 racing oil is the current recommended motor oil? Right?

Thank you one and all for your input. Just shows you what a great group of people you really are.

[RadioRoy]

Be sure not to use GL-4/GL-5 gear oil. The friction modifier additives will attack the synchronizers.

[bensherb]

Be sure not to use GL-4/GL-5 gear oil. The friction modifier additives will attack the synchronizers.

The friction modifers mess with the clutches in the OD. If you have the stock overdrive use GL-1. A gallon at Tractor supply co. is $18.