Which 75w90 gear oil for Subaru rear diff?

[dvancleve]

My closest O'Reilly has Castrol Syntec, Mobil 1 and Valvoline Synpower in stock. A quart will do it for my rear diff and I still have several LOL 5 off 5 coupons. It looks to me like the Synpower might have the best specs, the Syntecgear is a buck more than the others. I plan on Extra S up front, don't think the rear is finicky. Which would you choose?

Thanks, Doug

 

[Doug Hillary]

Hi,
Doug - Mobil 1 75w-90 gear lubricants work well in Subarus. Of course they must meet the stated component specifications

Castrol also make extremely good synthetic gear lubricants.

I have used both Brands over millions of kms with excellent results - at 1m km OCIs too!!

 

[randomhero439]

Redline 75w-90

 

[EddieCairns]

Stop worrying any oil that meets the spec will do.

Can you link to a diff UOA that shows a fail with a modern oil.

eddie

 

[dnewton3]

First, how about telling us what the OEM specs ... that's always a good place to start. I have no idea what the spec is; I don't have every lube requirement for every piece of equipment under the sun memorized ...
That being ranted, I'd "guess" that GL-5 will work, and is probably the spec. Or it might be J2360. There are a large host of lubes that meets these specs, and probably would do just fine.


Originally Posted By: dvancleve
Which would you choose?

Thanks, Doug


Of those three you listed, if they meet your Subie specs, then choose the one that is the least expensive. Your wallet will notice long before your diff does.

 

[Bottom_Feeder]

The rear diffs on these are not picky. Anything 75w-90 GL5 will work. It's the front transaxles that are picky.

Why not use Extra-S all around if you already have some?

 

[147_Grain]

My local Subaru dealer changed the factory fill gear oil at 5K for $28.00 in the front and rear differentials of my 2013 Subaru Outback (6-cylinder) and replaced it with the Amsoil's Severe Gear 75W-90 I provided.

Mechanic called over the service manager to tease him about striking gold (when he showed him all the shiny metal flakes drained out with the contaminated factory fill). This is a classic example of why we should change the break-in fluids early, even though the oil is not worn-out.

 

[SubLGT]

Buy the one that stays in grade longest and sheds the least iron. You will need to look at some UOAs here to determine that. I was not impressed with the UOA from M1 75W90 in my Subaru rear end.

 

[Cold_Canuk]

I dumped the front and rear diff fluids on my 2011 Subaru forester at 25000 Km's and I'd describe the fluid looked like silver honey........[censored]. I'm glad I didn't leave it in there until it the manufacturers OCI.

I went to Amsoil Severe Gear 75W-90

 

[147_Grain]

Break-in fluid is the exception to regular routine maintenance. The silver in the oil was likely ground-up metal particles. Your MPG should go up now there's less frictional resistance in the rear differential.

 

[dvancleve]

Originally Posted By: dnewton3
First, how about telling us what the OEM specs ... that's always a good place to start. I have no idea what the spec is; I don't have every lube requirement for every piece of equipment under the sun memorized ...
That being ranted, I'd "guess" that GL-5 will work, and is probably the spec. Or it might be J2360. There are a large host of lubes that meets these specs, and probably would do just fine.


GL-5 seems to be the only spec, 75w90 seems like the best viscosity especially if using synthetic.

Thanks, Doug

 

[buster]

I'm going with Synpower in the rear. 03 Forester.

 

[dvancleve]

Originally Posted By: SubLGT
Buy the one that stays in grade longest and sheds the least iron. You will need to look at some UOAs here to determine that. I was not impressed with the UOA from M1 75W90 in my Subaru rear end.


Originally Posted By: buster
I'm going with Synpower in the rear. 03 Forester.


Thanks guys

Based on the pds' for Mobil 1and Synpower, I think the Synpower looks a bit better. Not many UOAs, but both have good ones. I suppose it doesn't really matter anyway. Regarding Extra S, assuming I can source it in quarts it will be at least 2x the cost for the extra quart I will need for the rear diff and it doesn't seem to matter in the back. I think I will go with the Synpower if it is in stock (should be)...

Regards, Doug

 

[dnewton3]

Being in Chandler, you could easily use a dino 80w-90 as well; it's not like cold-flow concerns are an issue ...

If your OCI is not excessive, then any conventional lube would also work in a GL-5 variant.

Some folks will chime in about how dino's don't hold up as well, and that might be true, but the performance spec J2360 is pretty stout, and is not only met by many syns, but also some very common dinos. That spec is much more realistic than the simple GL-5; the J2360 includes aspects of heat/ox resistance and actual performance in use.


Check out my post here:
http://www.bobistheoilguy.com/forums/ubb...rue#Post3017738
and then follow the links to the info.


I'm not saying you should not use syn; I'm saying that you don't have to; it's a false sense ff security if normal OCIs are your plan.