Pennzoil vs Valvoline

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It's time to change the oil in the front and rear differentials on my Subaru Legacy and I can't decide between Valvoline and Pennzoil 75w90. I plan on getting their full synthetic. I'm expecting to be told "it doesn't make a difference" but wanted to make sure and see what kind of input I'd get. Car in question is an automatic, so no concern over what kind of impact the oil has on shifting since the AT and front diff don't share the fluid. Thanks guys!
 
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Flip a coin or use whatever is easier to get. But based on the PDS, Pennzoil looks to hold a slight edge mainly because of flash point. Pennzoil Synthetic 75W-90 / Valvoline SynPower 75W-90 Flash Point, °C: 201 / 163 Pour Point, °C: -45 / -45 Viscosity @ 40°C, cSt: 110 / 100 @100°C, cSt: 15.7 / 14.5 Viscosity Index: 151/ 150 Gravity, Specific @ 60°F: 0.860 / 0.886 You're not interested in one of the more robust gear oils, like Redline or Amsoil SG 75W-90?
 
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Nice rig, my brother has one and loves it. Seriously, I think any of the major brands syn gear oil is quality stuff. Personally I went with Amsoil because I think it's even better and since I don't change that fluid very often, I wanted the best I could get. Schaeffer's and Redline also make top notch gear oils.
 
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 Originally Posted By: Nayov
(Bottom line: "It doesn't make a difference" but stay away from RP.)
+1 I read that and opted for Valvoline Synthetic 75W-90, myself. I like RP motor oil for the OC intervals and driving I do, but I wouldn't use their gear lube.
 
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You may not want to use a full synthetic in the tranny/front diff of a Subaru. I've heard problems when doing so. The diff(s) likes it just fine but the tranny synchros don't like how slick the synth is, causing shifting trouble or something along those lines. Unfortunately, I don't have any links or info for you beyond that. http://www.nasioc.com might have more info somewhere.
 

fishbone

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 Originally Posted By: Bottom_Feeder
You may not want to use a full synthetic in the tranny/front diff of a Subaru. I've heard problems when doing so.
I guess you missed the part in my original post where I mentioned this is an automatic Subaru and the front differential does not share the fluid with the transmission ;\)
 Originally Posted By: hate2work
Nice rig, my brother has one and loves it.
Thank you! It's at Stage 2 and minus a couple tuning quirks I'm still working out, the car runs strong.
 Quote:
This is an excellent read. http://www.synthetic-oil-tech.com/Gear%20Lube%20White%20Paper.pdf (Bottom line: "It doesn't make a difference" but stay away from RP.)
You, sir, can read minds :) I found the exact same study and I was JUST about to post it. According to that one however, it looks like Mobil 1 syn gear oil comes out ahead of both Pennzoil AND Valvoline. I think it is also cheaper, Valvoline 75w90 synthetic is 12 bucks a quart here. I will re-read that white paper paying closer attention to the details of each test.
 

fishbone

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 Originally Posted By: Ben99GT
You're not interested in one of the more robust gear oils, like Redline or Amsoil SG 75W-90?
I'm always interested in the good stuff, but I think it would be largely wasted money. The car does not get tracked, nor does it see a terrible amount of wheel spin except winters when I have some fun :) I think something along the lines of M1, Pennzoil, Valvoline, would do just great.
 
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 Originally Posted By: fishbone
It's time to change the oil in the front and rear differentials on my Subaru Legacy and I can't decide between Valvoline and Pennzoil 75w90. I plan on getting their full synthetic. I'm expecting to be told "it doesn't make a difference" but wanted to make sure and see what kind of input I'd get. Car in question is an automatic, so no concern over what kind of impact the oil has on shifting since the AT and front diff don't share the fluid. Thanks guys!
I have never used, or seen, the Pennzoil Synthetic (75w-90). I have used the Valvoline 75W-90 in my '01 GMC 4x4 truck w/G-80 rear end and had some chatter problems in turns. I had better luck with Mobil-1. But I now use, and highly recommend, Amsoil Severe Gear 75W-90 lube. I am not an Amsoil fan, but this stuff (in my truck) is really worth the extra cost. I don't think you can find a better rear end lube than this stuff. \:\!
 

fishbone

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Well, I ended up buying 3 quarts of Amsoil Severe Gear at $12 a piece. Not a bad price for good stuff!
 
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