So i have been going nuts the past couple of days about what fluid to run! I currently just put in Amsoil 75w-140 in my car. The car is for sure stiffer to shift compared to 75w-90. The only reason i went ticker weight is because my car is making over 600wtq and i sheered off 3rd gear doing a pull a few weeks ago and dont want that to happen again. Running a ticker weight i think would protect the gears more.

Pretty much i dont wanna hurt the syncro's are anything in there by running a too thick weight.

You think im alright running the 75w140 amsoil?

 

I see in your sig that you have a Shep Trans. Your best bet is to inquire with them

 

Trans is no longer a Shep Trans went to a different person for the rebuild. Most people dont run a 6466 with a 2.4L and 40+PSI the TQ when it hits is snapping the gears. So i need a solution, just wondering what most people run with high horse power.

 

A Dogbox

 

thicker oil may not be great idea. thicker oil will not circulate as well. the right oil additives is more important. but its a double edged sword. the additives that make the gears slide over each other nice have that adverse effect on syncros. syncros need friction to work well.

best to reduce tq back below 600tq. fun goes out of the hobby real quick braking expensive parts. not to mention its no fun at all when car isnt drivable.

 

I have a dog box 1st and 2nd now. My main concern is to keep the gears and syncro's both happy. Usually its a trade off. I want a good medium.

This is true, my car isnt my DD tho

 

If anyone has ran 75w140 please post! How many miles on it. Any long term problems?!

 

I don't have anything to add here lol.. but I've seen your videos and you need this!

 

I will give a little on shift quality to preserve gear life any day.

 

Amzoil Severe gear 75-140 has a GL5 rating. It is not designed for a synchromesh transmission. The additive package includes friction modifiers that do not allow the synchronizers to work properly. I would stick with a GL4 rated oil that is designed for synchromesh transmissions.

I have used Amzoils Manual Transmission & Transaxle Gear Lube 75W-90 GL4, which is designed for a synchromesh transmission. I prefer to use Mitsubishi MR Six Speed DiaQueen Super Multi Gear Lube. I have found it shifts better then Amzoil.

Although you have not asked, Amzoils Severe Gear 250 is what I use in my Transfer Case and Rear Differential. It is noticeably quieter then any other fluids I have tried. I have used several and it is my favorite. DO NOT USE THAT RED SHOCKPROOF SHXX by Redline in anything. It cost me a fresh Transfer Case in fourteen miles!!!

Don