Wrong Gear Oil?
 

I think I read somewhere that if too light of a gear oil is added to the transmission/rear end it will cause it to leak. Is that true? I know both of mine are. It's light enough that it can drip off my finger and it's kind of dark. Also, what difference, if any, would it make in shifting?

Re: Wrong Gear Oil?
 

I use Texaco Meropa 680. It comes in 5 gallon buckets and I bought it from one of the oil suppliers in Des Moines when I lived in Iowa.

Re: Wrong Gear Oil?
 

Well, I do live 40 miles from there.......

Re: Wrong Gear Oil?
 

Its easy enough to change it and not worry about it.

I don't see any difference between 140w and 250w. Its available at Restoration Supply Co. The Meropa should be just fine also.

From what I understand the 600W available today is doctored up 140w.

Is the transmitter actually leaking, or, is it the u-joint clamshell ?

Re: Wrong Gear Oil?
 

I haven't checked that close yet. Too many other issues. I think it was on the bottom of the transmission.

Re: Wrong Gear Oil?
 

Probably leaking from the reverse idler and cluster gear shafts. The vendors have a kit that stops that annoying leak. https://www.snydersantiqueauto.com/P...earchByKeyword

Replacement shafts have a 'o' ring.

Re: Wrong Gear Oil?
 

The recommended lubricants are dictated by the manufacturer. Outdated lubricate grade ratings generally always have a modern equivalent. Seal technology back in the early automotive era was not as good as it is today but it kept the majority of the lubricant inside where it belongs. It's after the seals deteriorate and clearances wear when it gets harder to keep the lube in. Renew the seals and seal up any clearance gaps and the units should still hold their mud.

Re: Wrong Gear Oil?
 

Another issue is that the A tranny in not synchronized. The heavy dope helps the shifting process. I’ve not tried thinner oil but would think leaking would also be an issue.

Re: Wrong Gear Oil?
 

Mitchell recommends 85W-140 GL5 gear oil for their transmissions and overdrives for the Model A. Oils have come a long way in 90 years and the modern oils have additives to maintain the oil film under pressure. The 85W-140 is fairly thick oil. I use it in my transmission and rear end.

If the transmission is too full it will leak. New gaskets and seals will stop leaks.

Re: Wrong Gear Oil?
 

My experience: I have used Lucas Oil Stabilizer in my A transmission for years. Makes the shifter silky smooth. The "600W" oil I got from the vendors was not good. Try it yourself, Stopped the oil drip on mine too.

Re: Wrong Gear Oil?
 

I have used straight STP in transmission/differential/steering box for the last 15-20 years.
Many miles and no problems.

Re: Wrong Gear Oil?
 

I'll bet it takes a while to change out that STP viscosity builder product. Straight SAE 250 would be easier to change than that stuff.

Re: Wrong Gear Oil?
 

A thin gear oil will make gear changing more difficult to do silently IMO.

Re: Wrong Gear Oil?
 

One thing to keep in mind when reading lubricant specifications, Gear Oil numbers are different than SAE Oil numbers for equivalents, and I think the old 600W, SAE 50, and 90W Gear Oil are all pretty close in terms of viscosity.

Re: Wrong Gear Oil?
 

600W is more in line with 180-240W. 140 and 250 work fine as stated. 90 is to light. This is discussed very often here.

Re: Wrong Gear Oil?
 

Re: Wrong Gear Oil?
 

The Society of Automotive Engineers had different systems for grading viscosity standards between motor oil and gear lubricant products. SAE 50 motor oil is in the same viscosity range as SAE 90 gear lubricant. The API is also part of the current rating system. All are still SAE or ISO rated but the type of lubricant has to be included to tell what the rating is for. Motor oils used ZDDP for tappet protection but gear lubes have extra pressure or EP additives designed for gears for an EP rating in similar fashion as grease products but grease products have there own ratings and extra pressure additive packages so they are all in their own separate categories. ATF & Hydraulic fluid are also in different categories.

The SAE is still used in the US but the International Standard Organization or ISO still takes precedence in the modern era.

Re: Wrong Gear Oil?
 

when changing the STP in trans and diff, I just open the drain plugs and come back a few days later......
steering box does not get changed, just topped off as needed.