VMC Speedster Gear Oil

The Motul is great oil. There are syncros in your transaxle, and no LSD unless you specified it... and even if you did, it'd be a TBD with no clutches, so you could use anything you want.

There is a raging eleventy-billion page debate on TheSamba about GL4 and GL5 oil. There is some concern about brass being incompatible with GL5 oil, but there's not a rash of disintegrating syncros in old transaxles running modern gear oil, so I don't know.

I run the Motul.

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The only important thing to remember about changing transaxle oil is don't pull the drain plug until you've managed to get the fill plug open.

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Thanks for the tips guys.

I found the Sta-Lube 85W-90 GL-4 multi-purpose gear oil at NAPA auto parts and it says it safe for yellow metals.  Has anyone tried this gear oil?  I see some YouTubers we're using this in their transaxel fluid change videos.

@Sacto Mitch posted:

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The only important thing to remember about changing transaxle oil is don't pull the drain plug until you've managed to get the fill plug open.

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Was that a hard learned lesson?

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@LI-Rick posted:

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Was that a hard learned lesson?

It must have been for someone, as it's usually the first thing you read in any printed instructions for changing transaxle oil.

I guess they figure we all check and top up engine oil a lot more often, but tend to forget about the gearbox.

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@Sacto Mitch posted:

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It must have been for someone, as it's usually the first thing you read in any printed instructions for changing transaxle oil.

I guess they figure we all check and top up engine oil a lot more often, but tend to forget about the gearbox.

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I was expecting a good story from an endeavor gone awry.  Now I'm disappointed!

I use the Motul Gearbox. Similar trans: IRS, 3.88.   My first excursion into this required a trip to Harbor Freight to get the correct Allen wrenching.  I suppose the best other tool is a hand operated oil pump to get the new oil in.  Not having such a thing handy at  the moment, I figured to remove the right rear wheel and use a long clear plastic hose, which was at hand. awkward, to say the least.

@pkdfw  another fun fact...put bottles of gear oil in  bucket of HOT WATER while draining....it will flow in way smoother  & faster  when refilling

@El Frazoo posted:

I use the Motul Gearbox. Similar trans: IRS, 3.88.   My first excursion into this required a trip to Harbor Freight to get the correct Allen wrenching.  I suppose the best other tool is a hand operated oil pump to get the new oil in.  Not having such a thing handy at  the moment, I figured to remove the right rear wheel and use a long clear plastic hose, which was at hand. awkward, to say the least.

A pump is $10 on Amazon prime, and about the same price from any FLAPS.

I did some more research on the GL-4 gear oils today and found that several companies still make the GL-4 gear oils for the classic cars with yellow metal components.  Here's the ones I found:

Sta-Lube GL-4 85W-90: https://www.amazon.com/CRC-Sta...MC/ref=sr_1_1?sr=8-1

VP Classic Gear Oil GL-4 80W-90: https://www.amazon.com/dp/B07W...c_wl_lv_ov_lig_dp_it

Driven Racing GL-4 80W-90: https://www.amazon.com/dp/B072...c_wl_lv_ov_lig_dp_it

PennGrade1 GL-4 80W-90: https://www.amazon.com/dp/B0CHG3X79B

The PennGrade1 originated from Kendall racing motor oils back in 1965 and I used to use their motor oil in my Pontiacs.  Amazon had the PennGrade1 at a very reasonable price for 4 quarts so I decided to give that a try to see if it made a difference to the GL-5 85W-140 that is in my car right now. 

The shifting is stiff and some times it's hard to get into first and second.  As my car is just completing its break in, the clutch cable tension had to be adjusted as the cable stretched and there was quite a bit of play when pushing down on the clutch pedal before engaging - about 2.5".  I adjusted it so there's about an 1" now.

Let's see if swapping to a GL-4 80W-90 gear oil makes it more smooth after re- tensioning the clutch cable.

You'll definitely notice easier shifting with the 80W/90. If you have a super-diff, it might be louder.

Thanks Stan.  BTW, I also seen some posts that said having the car up on a lift with the IRS hanging down can affect the fill level.  Is there any truth to that?

I have a super wide body Speedster with the heavier wide rear wheels so I was thinking of removing them to take the weight off the suspension to fill the transaxle just in case having the suspension hanging caused less fluid to go back in.

I can’t imagine it making much difference. I have IRS. I just lift the car, drop the oil, and pump new in until I reach the bottom of the access hole, then put the plug back in.

I would think that would be true with swing axles, which use the grease in the transaxle, but not for IRS.

Thanks Lane and Stan for the confirmation.   I hope to have my gear oil before next weekend and will do the transaxle service and report back on the difference of the GL-4 vs the GL-5.

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My local mechanic, a respected air-cooled dude with over 30 years experience, always tries to limit the 'drop' of swing axles when a car's on his lift — not to control the flow of the oil but to limit the stretching of the axle boots. If you drive with one split, it's a real mess.

A bolt inserted like this will limit the axle travel.

On an IRS car, you may not lose your gearbox oil if a boot splits, but you can quickly damage the U-joint.

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@pkdfw I don't think GL-4 or 5 is a big deal today. Right now I'm using Lucas in my Vees. Because we are always cornering and the gear oil sloshes from one swing axle tube to the other, we run the oil level about an inch below the fill hole. Obviously this does not apply to street-driven swings or any IRS box.

If your trans is new or rebuilt you should change the gear oil after the first 1000 miles or so(it could be 800 or 3000, my memory is fuzzy).

I did notice better cold-weather shifting when I switched to Valvoline synthetic 75w90 in my Spyder. It's my go-to after I run the cheapest crap I can find for break-in. You'd be surprised how much metal fuzz you'll find on the drain plug at the first change.

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@DannyP posted:

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...You'd be surprised how much metal fuzz you'll find on the drain plug at the first change...

You're right, Danny.

Once you grind through all the synchros, they do run a lot cleaner.

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@DannyP posted:

@pkdfw I don't think GL-4 or 5 is a big deal today. Right now I'm using Lucas in my Vees. Because we are always cornering and the gear oil sloshes from one swing axle tube to the other, we run the oil level about an inch below the fill hole. Obviously this does not apply to street-driven swings or any IRS box.

If your trans is new or rebuilt you should change the gear oil after the first 1000 miles or so(it could be 800 or 3000, my memory is fuzzy).

I did notice better cold-weather shifting when I switched to Valvoline synthetic 75w90 in my Spyder. It's my go-to after I run the cheapest crap I can find for break-in. You'd be surprised how much metal fuzz you'll find on the drain plug at the first change.

Thanks @DannyP. Based on the VMC specs I got from Greg, the break in mileage on the VMC Speedster's transaxle is 500 miles.  So it's getting time for me to swap it out and I'll experiment with the 80W-90 weight to see how it differs from the factory 85W-140.

I'm eager to see how much metal shavings I find on the magnet. 

@Sacto Mitch posted:

.You're right, Danny.

Once you grind through all the synchros, they do run a lot cleaner.

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Synchro dust is brass, and doesn't stick to the magnet.

The steel filings are mostly from gears and bearings and synchro hubs wearing in. Or in the case of swing axles, parts of fulcrum plates. All that will stick to the drain plug or plugs(pre '68 trans cases have 2 drain plugs).

Brass will come out with the oil, which is why you want to dump it hot when the filings are all in suspension.

I did the transaxel gear oil change today using the lighter 80W-90 weight GL-4 oil and it made a difference in the way the gear box shifted.  Easier to row the gears and less sticking when going into 2nd and 1st.

I also noticed what Stan said too.  You can hear the transaxel a bit more and it's a slightly higher whining sound than before with the thicker oil.

I'm OK with smoother shifts.

I use Swepco 201.