I own an AP1 my03 since 5 months or so. Car is in excellent shape just 29k miles.

I'm the 3rd owner. I suspect previous owners never changed transmission oil and diff. Also I'm not sure what were their driving habits.

For a peace of mind I'm planning to change the fluid at 30k and run my own maintenence record.

I searched alot and I read a lot about the fluids.

So far I will go with OEM MTF type II transm fluid.

For the diff I chose Mobil 1.

I went to autozone and when I got there they had

Mobil 1 75w-90 LS and 75-140 LS both GL-5 but the second bottle is rated for small trucks and diesels!

I read here somewhere here I should use the 75-140 due some SAE ratings changes in the decade.

I'm a spirited driver and car will see local track about 1-2 times a year.

I'm confused about which one should I use.

I know it's an overrated topic, but I'm quite confused.
I appreciate your help. Thanx in advance.

 

75-90 is what you should use

 

Actually the SAE change that you mention means that you should use 75-110. Or straight 110 if you can find it.

If your only choice is 75-90 and 75-140, I would stick with the 75-90.

 

I'm using Amsoil 75W140,GL-5 with my 4.56 gears;less noisy...

 

I forgot to mention I leave in Puerto Rico, temps here never see freezing point.

 

You wont regret it

 

I'm running Amsoil's Severe Gear 75w-110, I think it would be perfect for your use, the extra viscosity over a 75w90 would be a benefit. A SAE 90 fluid would be perfectly fine as well if you can locate some in your area. A 75w140 would be good for hard use or track/racing conditions.

 

So due the high temp here, and spirited driving I guess my better bet is 75w-110 I will look aorund to see what I find.

Thank you everybody

 

LE-1605 IS the best way to go!!!

 

this is what i have in my car but i'm switching to amsoil or redline soon. i only used this cause the original owner provided me with 3 quarts of it. its too thick in my opinion