Gear oil brand?

[Yeret]

My rear end is well due for some fresh oil, however I'm not sure what my best bet is as there are qutie a few choices out there. Also, I'm unsure of the weight I should go with.

I'm almost certain my rear end is not a limited slip, however most oils I see supposedly have a limited slip additve anyway...

I've read that one should use 75-90 for general use, but 75-140 for heavy towing. I don't tow with my truck, however looking at the oil, I think it might be better to use the "heavier" stuff as my rear end has 170,000 miles and doesn't look like it's ever seen an oil change (the stuff in there looks more like tar than oil). I just think the 140 may provide better overall protection, but I'm a newb with oil weight/theory, so please correct me if I'm wrong (also, the 75-90 is MUCH cheaper).

The Lucas Oil stuff is only $12 a quart (75-140) but I've read mixed reviews on it.

Royal Purple gets better reviews but is over $20 a quart.

Any input is appreciated!

 

[BBartow]

FSM says 75W-140 for the front and 80W-90 or 75W-140 for the rear. I run Valvoline Full Syn 75W-140 front and rear. I buy mine at $12.99/Quart and never had any issues. I still add the friction modifier for the rear lsd even though it says it doesn't need it, I was told to do so anyway. You should be fine with 75W-90 front and rear as well.

 

[Merc225hp]

Mr. BBartow has you covered.

I use Mercury Marine Quicksilver High Performance gear oil front and back works great for me, most would not go this route. Next choice would be Liqui Moly then Redline. No Lucas here never will be. Basic rule if you are not sure if you have an LSD add the friction modifier this covers you and hurts nothing.