Can i use a motor oil for my gearbox?

Question

The recommended gear oil for my car is 75w-80,I found this not suitable for the hot climate here in Egypt so i want to use more thicker oil for the gearbox,will it be a good idea to use a motor oil 20w-50?

the 75w-80 one is synthetic

Answer 1

20w - 50 is not as heavy as is the recommended 75w-80 so I suspect it would perform poorly as a replacement for the recommended.

Is the hot climate causing lub failure or is the oil degrading? If degradation is the problem, perhaps a synthetic oil at the 75 w - 80 rating would be a better idea.

Going to a heavier oil is probably not wise - as the oil may not flow fast enough in critical parts to assure lubrication.

Is there any chance sludge build up has happened and this has prevented the gear oil from flowing uniformly? Also is there a transmission oil cooler that is plugged?

Can you add a transmission oil cooler for added cooling?

I would consider these before I went to other oil weights.

Answer 2

motor oil is definately not recommended.

you didnt say what type of car or trans so we have very little to go on. but people that make thousands of dollars a year said your car's trans takes 75w80.
think about that.
if youre still convinced this isnt "suitable" as you stated, try to see if this vehicle was built with and without a cooler. if you dont have one because this particular vehicle wasnt intended for use in egypt, try to get the factory cooler, or a suitable alternative.

HOWEVER,
if your bound and determined to use motor oil, i suppose it is possible. hondas used motor oil in the 80's in their manuals, so its not completely unheard of. even then, i would still recommend something as close as possible to the original spec. so use straight 50 weight.
BEWARE that you will experience very different synchronizer characteristics and will probably grind a couple gears because the blocker rings will "cut through" the motor oil much easier and faster than if you were to follow the specs.

and no, this doesnt mean the speed gears will be brought up to speed faster thus enabling you to shift faster.

expect overall transmission life to be reduced by no less then 20 percent.

Answer 3

Temporarily yes. If the oil weight is too far off, you'll burn up the gear box. Gear box oil is usually synthetic. Contact the manufacturer and tell them your problem. They will have a suggestion.

Answer 4

Gear oil and engine oil have different additive packages so even if you got the viscosity close enough in the long run it would not be a good idea.

Answer 5

What are you nuts?? What's next? Vegetable oil in your gearbox? Don't be a fool, always follow your manufacturer's recommendation. They build the car, they are the experts, they should know what's best for your car. Good luck.

Answer 6

no you can not use motor oil in a gear box go into your owner manual and look to see what it takes.

and if they say 75w-80 which is gear oil t hat iswhat you have to use.

auto mech. 20 yrs

Answer 7

The higher the number, the thicker the oil. What you are proposing is actually THINNER, completely opposite of what you say you intend. However, in hotter areas, you *should * use thinner oil like 15w50, but that's for engine. Gear oil should be MUCH MUCH thicker than that.

http://www.carbibles.com/viscosity.html

Answer 8

I WOULD NOT RECOMMEND THAT YOU USE THE 20W-50 IN PLACE OF THE 75W-80.

I BELIEVE THAT IT WOULD BE POSSIBLE THAT YOU COULD BURN UP THE INTERNAL GEARS WITH THE LIGHTER OIL

Answer 9

If you dont like your gearbox very much use the wrong type of fluid and you will send it to the junk yard PDQ.

Answer 10

no, just get a thicker and heavier gear oil, it comes in differen't weights.