Corvair Forum

I just completed a rebuild on my '63 Monza Spyder engine. Initial checks are promising...good compression, no unwanted engine noises, runs great. I put UV dye in the engine oil to check for leaks, and the engine looks tight. However, I'm puzzled that the UV dye shows up in the 4spd transmission and differential. I re-sealed both while I had the engine out. Unless Sta-lube contains it own UV dye, I've got a problem. Has anyone run into this? The new front engine seal installed without a hitch. I'm looking for suggestions. Thanks.

The tranny/diff oil must contain a substance that shows under UV light. There is no oil-carrying connection between the engine and transaxle, and any oil leaking past the front seal will leak out of the bellhousing.

If you filled the trans yourself, do you have any extra oil? Or, pick up a bottle of the same oil you used. See what the new stuff looks like under UV.

Hi Steve,

Now why didn't I think of that!

At your suggestion tested the Sta-lube GL-4 under the UV light, and it reacted to it.
Thanks Steve, I'm going to sleep better tonight.

Is that Sta-Lube their 85W90 GL4? Your sig says Phoenix so I'm guessing it's warm outside. How well does your transmission shift between gears when it's "cold" (meaning the first couple of shifts). Here in North Idaho, that product blocks the synchros until the oil warms up. (at say 55F) I had to change my gear oil in two cars to another maker's 80w90 GL4 to get them to shift in our climate.

I haven't done any cold weather driving yet. I'm using Sta-Lube GL-4 85W/90 and shifting is easy and smooth right now.

Although I did have an issue with stiff shifting that turned out to be the tube that connects the shifter to the transmission. In the tunnel, at the aft of this shift tube, is a 6" foam rubber hose wrapped around the tube. I suppose it's there to protect all of the other cables, wires and rods in the tunnel from the shifer movement. This foam rubber hose was pinched between the floor bottom and the tunnel cover causing drag on the shift tube. The cover was slightly pushed in, so I re-formed it. There was still some drag after that and I ended up removing foam hose for now. Not the best solution, but a band-aid until I find time to fix it properly. My only point is that your problem may be something other than viscosity.

Definitely a viscosity problem in my cases. I changed two good running Corvairs to the 85w90 and instantly had problems with both. Start out in first, then impossible to shift to second or back to first. Drive for five minutes and both were OK after that. Both cars same problem. Drained and switched to 80w90 and both cars went back to normal. In speaking with Richard Widman (oil guru), he pointed out that the cold viscosity (centistokes?) of the 85w90 was TWICE that of 80w90. That was the problem. Note the the OE spec oil for Corvairs was 80wt. May not be a problem in Phoenix's warmer climate.

Dealing with gear lube, I lived in Nebraska driving a Volkswagon. During the winter months you were lucky to get it in gear in any direction upon start up. My dad switched it over to AmsOil and it was like night and day. The synthetics just don't seem to get as thick when cold as the conventional oils do. I am not an oil guru, but I have to admit I do like the synthetics. My engines stay really clean using them and the manuals shift easy.

Now that you mention it, I have a 2006 C6 Corvette that wouldn't go into first gear on cold mornings until I switched to Royal Purple in the transaxle.

Interesting discussion. I rebuilt the 4 speed in my 64 a year and a half ago. I refilled it with the Amsoil stuff everyone recommends (I've been using Amsoil products my whole life anyway). After the rebuild, I can shift all the way up with no issues, but when I try to shift from 3rd back down into second...the synchro doesn't spin up. I have to shove it half way into first gear and then quickly back down into 2nd if I want to shift down...which is basically every turn I take. It's quite annoying.

Best I could think was that maybe the Amsoil is so slick that the synchro isn't grabbing the cone and spinning up. I bought some conventional stuff and was going to swap some of the fluid out and see if it makes any difference.