synthetic gear oil?

[acvolt145]

Mid-week next week hope to get some time to work on the m109a4 and change the gear oil out. Just wanted some opinions as to what you guys prefer as i don't have tons of experience with big trucks. Was debating on going synthetic as most of my cars and trucks now run it, or just go with the cheapest stuff and change it more often. looking around my shop i seem to have quite a bit but not enough of the Mobil one synthetic 75-90 but seems kinda a thin, I also got some normal 85-140, just wanted some opinions on what to use.

 

[dittle]

Don't know of a reason why to go away from the GL-90 that comes in the trucks. It works just fine and I doubt you're going to drive the truck enough to wear that oil out.

 

[Flyingvan911]

There are several lubes that can be used. GL-1 90W and GL-5 80W90 in the differentials. You can use GL-1, GL-5 and 50W motor oil in the transmission and transfer case. There are several threads on what people prefer and some of them so deep into the science of why one is better than another. Others turn into our own private civil war for lube type supremacy.

I use GL-5 in my deuce and it works well. Be sure your lube is MT-1 yellow metal safe for the tranny and trans cases. The brass synchros don't like some of the old stuff.

 

[acvolt145]

Thanks guys, unfortunately i do not have a a2 yet, so in my a3 trans i need to run stuff like the dexlll or transynd yeah i can stick with the gl-90 without a problem just was wondering if it was worth the switch.

 

[paulfarber]

Use synthetic oil only if you hare in a high heat situation (over 250F) otherwise you are wasting money. GL-1 is a poor choice.. its straight oil with no additives save some anti-foaming. You want all the additives you can get to reduce wear/friction/foaming/going rancid etc. Your deuce has had GL-5 in it for 20+ years... how many failures have been directly attributed to GL-5 breakdown? HInt: none.

 

[Westech]

I use 30WND in the trans and 80/90 GL5 in the axles and transfer case. Have had no problems and Trans runs cooler and shifts better.

 

[pctrans]

If you have ANY leaky spots, synthetic will find it! I would stick with GL-5 or 85/140.

 

[ctmustang]

You might wanna try the search function as this has been covered in about 739 threads. Youre almost certain to find the answer to your questions there.
CT