mhartpence

I just recently purchased a 1960 convertible 3 speed.
I would like to start changing the fluids and other things to make sure I don't get stuck on the road.
I thought I would start with the transmission fluid. I know the engine oil was changed this year.
What would you recommend for the best 3 speed manual transmission fluid out there??
Thanks

Geralds57

Welcome to the forum! It probably doesn’t need changing but check the level to be sure. Any manual transmission fluid would work. Nothing fancy. Show us some pictures when you can. We all like to see new owners cars.

Vette5311

Regular gear oil is ok but add a bottle of Lucas manual trans additive. Really works.

SDVette

Welcome to the forum.. and from me, to club 3-speed!

My car sat for 40 years. I did a drain and fill on the transmission (with GL-4 spec lube) and Differential (GL-5 spec lube). I do not have a positraction rear.
If you have Posi, you'll need a limited slip additive (or an oil with it pre-added) in the rear end.

There is some "controversy" over GL4/GL5.. Technically, GL5 is a "better" lube.. However, some mfgs claim the additives used in GL5 can attack the soft metals (synchros) in our old transmissions. I don't have experience or take a position on this.. just reporting it.

My fluid changes were 5 years and 4000 miles ago... no problems at all.

You can find lots of general info like this in the FAQ thread pinned to the top of this section.

Fred

MikeM

I bought my '65 three speed car in 1972. Checked the oil level and it was full. Checked it again in 2001 and it was still full. No signs of leaking. Next owner that buys it at the estate sale might want to check it.

SDVette

I think that's sound advise for a car that is driven semi-regularly.
But after a 40 year sit, I assumed there was some moisture damage done to the 'dry' parts.
I drove the car for a few miles, then did the drain/refill.
There was a lot of crap in the trans fluid.. the diff fluid looked OK.

Noticeably less whining and smoother shifting after the drain/refill too.

dcamick

mhartpence,

For what it's worth.....I have always used Stay-Lube.................

Best,

dcamick

mhartpence

Thanks for the info. I believe this car sat around also. Sometimes the shifting and accelerating is not just what it should be.

59BlueSilver

i do also, GL4.

Dan Hampton

Don't bang any hard shifts in second gear. Those synchro units, which are part of the low/reverse sliding gear, are very weak and next to impossible to find these days. You have to buy an entire transmission to get one and then you don't know the condition of the synchro until you open up the box. Not a good way to buy a replacement part.

Mike M is correct. Don't overthink the fluid issue. Run it, get it hot, change it and don't worry about it for another decade. Monitor it for leaks.

SWCDuke

The original oil spec for both manual transmissions and axles was MiL-L-2105 hypoid gear lubricant. In the seventies the milspec was cancelled and the commercial API 80W-90 GL5 was substituted. Brand makes no difference... just make sure the bottle has the API "donut" and says "SAE 80W-90 GL-5. If the axle is Positraction it will need at least one bottle of friction modifier, NAPA NCB 4285B.

Duke