Carquest Grease and Lube EP 90 GL-4 Gear Oil, 1 Gallon

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Mar 11, 2023
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Hello, i have a 2008 Mazda3 2.0 with manual trans. Denver Colorado temperature which not too hot or cold. My trans. requires either 75W90 GL-4 OR GL-5. Many forums suggest using only GL-4 and not GL-4 and GL5 comparable. i just want to something that not so expensive like Redline or MT90 in the car. Kind of on budget. Has anyone ever use Carquest Grease and Lube EP 90 GL-4 Gear Oil. $25 for 4 qt. (1 gal)---SAE90. Also since it a GL-4, do you think it is acceptable for my transmission.

Thank you.

 
Find one of these:

My recommendation is to up the budget and use Amsoil, Redline, Ford, MPT... fluid. A good GL4 75w90 is cheaper than a new transmission.

Your climate is also cool enough for Nissan/Hyundai/Kia 75w85 GL4 from their parts bin, but I haven't priced those in a long time.
 
Walmart has Supertech 80w90 gl5 for $20/gal and the 75w90 full synthetic for $10/qt. My store was out of the gl5 blend 75w90 at $8/qt. Try those if on a budget or if not in a hurry by 2 qts/payday of full syn like M1, Redline or Valvoline and do it next month. Nothing really wrong w CQ if that is what you want and can afford, sure your trans will appreciate clean fluid
 
Do not use GL5. It will damage your transmission as it has yellow metal inside. Use GL4. I use Redline MT90 75w90 in my 2011 Mazda6. It is expensive ($22/qt) on Amazon but cheaper than a transmission. Use another brand if it meets the specs and is less expensive if you desire. If I recall you only need about 3 quarts. It is a little hard to find a GL4 75w90 but I use Redline because it’s easy to find online. I change it every 50k miles.

Whatever you use make sure it is GL4, 75w90. I wouldn’t use the Carquest gear oil. It isn’t a 75w90. Don’t skimp out on a non-spec gear oil. Gear oil isn’t like API spec engine oil where you can blindly use a newer more modern API oil in place of an older spec.

 
Last edited:
Do not use GL5. It will damage your transmission as it has yellow metal inside. Use GL4. I use Redline MT90 75w90 in my 2011 Mazda6. It is expensive ($22/qt) on Amazon but cheaper than a transmission. Use another brand if it meets the specs and is less expensive if you desire. If I recall you only need about 3 quarts. It is a little hard to find a GL4 75w90 but I use Redline because it’s easy to find online. I change it every 50k miles.

Whatever you use make sure it is GL4, 75w90. I wouldn’t use the Carquest gear oil. It isn’t a 75w90. Don’t skimp out on a non-spec gear oil. Gear oil isn’t like API spec engine oil where you can blindly use a newer more modern API oil in place of an older spec.

Just out of curiosity, if the OM specifies GL4 or GL5, why would using GL5 damage the trans?
 
Thank you everyone for the quick response. Since i am going to keep this car for a while, i just have to spend a bit more for the right kind of oil.
 
Just out of curiosity, if the OM specifies GL4 or GL5, why would using GL5 damage the trans?
My understanding is that it won’t damage the transmission, but it will result in less than optimal shifting characteristics due to the extreme pressure additives in the GL-5 fluid.

I know that I put GL-5 fluid in my Corolla transmission and drove it about 90,000 miles with no problem. I didn’t notice any difference, but I’m not exactly a racecar driver. At the time I hadn’t been enlightened and the manual said GL-5 was OK. It didn’t seem to be a problem. But again, maybe I’m just not a sophisticated enough driver to notice.
 
Back in the day, it wasn't common for GL5 to have LS additives. If you can find a good LS additive free GL5, look those recommended for Subarus, you'll be fine. I haven't felt an issue with extra EP additive and the transmissions shifted fine. Some of the GL5's equipped with LS additive have relative low doses of LS additive and can be tolerable. I don't want the negatives of LS additive in my manual transmissions.

Stick with the GL4 since its a no brainer.
 
I can attest that the Redline MT-90 is the way to go, if you do need a GL4 rated oil for trannys with yellow or brass metal inside.

Been using it for several years on my older SM-465 Transmission in my old 1951 pickup. It works great and shifts WAY smooth.


EM
 
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