Ultra1Plus SAE 75W-90 Synthetic Gear Oil API GL-4 (QT)

Hard to find gl4 oil these days this seems to be real good oil transmission shifts well and is quiet. I like the clear bottles but wish they had the smaller lids.

Good stuff!

GL-4 for manual gearbox transmission, once you go synthetic, stay synthetic in the manual gearbox

This is my third swap of gear oil in my NC4 Miata since I bought it earlier this year. First was Redline MT90, then an 80W-90 viscosity that I should not have tried. This oil so far is much better - definitely worth a try in any Miata. If I still had my 90 NA, I definitely try it - I tried everything else in that one, including Motorcraft, and nothing worked well.

I've worked in the automotive industry for nearly 20 years and I know the importance of using the specified fluids. For this application I couldn't find anything locally and most of the products I found online are for high performance use and are prohibitively expensive. This was just what was specified and the price is reasonable

It shifts and sounds like a new transmission. I changed the gear oil just for maintenance purposes on my 400,000 mile 1987 Nissan pickup. It didn’t have any meaningful problems but it was on the noisy side and a down shift from second to first on the move basically wouldn’t work. Now it shifts up and down through the gears perfectly and is practically silent. I’m guessing the smooth shifting is due a lack of friction modifiers that practically all other 75w90 has in it. This stuff seems to more slippery than other gear oil too.

My transmission had 70K logged and I wanted to swap the fluid to keep it going. The warranty is that the fluid put in at the assembly plant will last its life. Well, duh! If a transmission dies because the old fluid is gunky and has lost its viscosity, then I guess that'd be the life of the transmission and they're covered. Synthetic transmission fluids that were up to spec for my car were all very expensive except for this, which didn't bust the bank. But, it's working beautifully despite the price. Shifts are as crisp as the day the car was new. We're in a Minnesota cold snap and the transmission isn't sluggish at all. It's good gunk.

Great oil and it's what you should use if you have a transmission with yellow metals inside.

Transmission works great without spending $60 on GL-4 fluid. Would definitely buy again.

Added 4.5 quarts to a fully drained 2011 Nissan Xterra manual transmission, shifts are noticeably harder when first starting out. I selected this for price and ended up buying a case of 12 bottles. Hard to locate GL4 gear oil, I will leave in for 6 months then drain out and replace with OEM Nissan fluid which had much smoother shifting.