Synthetic Gear Oil

[Zorba]

I am about to swap the differential fluid in my 1999 and 2006 Subaru Legacies, both autos. I noticed this weekend NAPA had some royal purple gear oil and I've seen some other brands online. Is there a benefit to using Synthetic gear oil in the differentials over dino? And if so what is a good brand that you can buy at a common store (don't want to order online).

Well I am asking about Synthetics, what are people's feelings about using Synthetic ATF in an auto tranny as opposed to the normal stuff?

 

[BlackTigers]

Gear oil or ATF? I'd seriously recommend just putting ATF in an ATX...the synthetic stuff is friction modified better and lasts longer.

Don't put gear oil or the Synchromesh stuff in there - it's modified for an MTX, which has different friction properties.

 

[Zorba]

I was really asking about synthetic gear oil for the differentials and synthetic ATF for the transmission. I'll try to make that more clear in the OP.

 

[Jabbernyx]

I've heard nothing but good things about Royal Purple stuff (ATF and engine oil mostly), but that said, it's way too rich for my blood.
Just recently did a tranny "flush" on the LS V8 and used Valvoline full synthetic Mercon V. Needed a whole case and the price differential for RP would've killed me. IIRC, cost was just slightly more than the dino stuff.

 

[LOUISSSSS]

.

 

[StageLeft]

It's better but normally hard to quantify syn vs dino benefits.

 

[mooseracing]

For the diffs, if you drive in cold climates syn does help.

The auto I would only run it if it meets your trannies specs. For manuals, I won't run it again.

 

[SoulAssassin]

I run Amsoil...I would either do that or Redline or Royal Purple. All good stuff. I really should put the cheap crap in because this is in my Jeep and I end up having to change the fluids every 6 months after doing deep water crossings.

 

[NutBucket]

Do yourself a favor and run OEM fluid. Its usually your best bet.

 

[joutlaw]

I used a synthetic blend the last time I changed the fluid in my Z71's front diff. It was $10/quart I believe.

 

[Vette73]

Originally posted by: NutBucket
Do yourself a favor and run OEM fluid. Its usually your best bet.

OEM fluid? WTF is that. All auto makers just buy it bulk. Most get it from Exxon/Mobil and slap their name on it.

 

[CupCak3]

Originally posted by: SoulAssassin
I run Amsoil...I would either do that or Redline or Royal Purple. All good stuff. I really should put the cheap crap in because this is in my Jeep and I end up having to change the fluids every 6 months after doing deep water crossings.

+1 for amsoil

 

[Gillbot]

Personally, I think amsoil is overrated and their mileage claims are laughable at best.

 

[SoulAssassin]

Originally posted by: Gillbot
Personally, I think amsoil is overrated and their mileage claims are laughable at best.

25K between changes is rather crazy. I do it once a year in my Jeep which works out to every 8-10k. Probably could go longer but I abuse the hell out of it.

 

[Gillbot]

Originally posted by: SoulAssassin

Originally posted by: Gillbot
Personally, I think amsoil is overrated and their mileage claims are laughable at best.

25K between changes is rather crazy. I do it once a year in my Jeep which works out to every 8-10k. Probably could go longer but I abuse the hell out of it.

It's a complete joke anytime a manufacturer puts an arbitrary number on an oil change interval. You need to consider the environment and service duty of the vehicle first before you can determine a proper oil change interval. The Z28 in my sig is LUCKY to get 3k miles on it's fully synthetic oil due to fuel dilution, but then again the Z28 sees severe service duty at the track often.

Furthermore, while the oil may be able to maintain lubricity for 10k+, the oil filter probably cannot. I bet 99% of the people who buy into this 10 and 25k garbage toss this oil in thinking it's a cure-all and they never change their filter until they change the oil.

 

[CupCak3]

Originally posted by: Gillbot
Personally, I think amsoil is overrated and their mileage claims are laughable at best.

Do you have anything to back that up besides it "doesn't make sense to you" or "you know better"

I've had amsoil in my car for the past 125k miles, with a once per year change. Engine still running strong.

 

[LS8]

I use Royal Purple in the rear difs if all my RWD cars and my 4x4 truck with great success. Awesome product.

 

[Gillbot]

Originally posted by: CupCak3

Originally posted by: Gillbot
Personally, I think amsoil is overrated and their mileage claims are laughable at best.

Do you have anything to back that up besides it "doesn't make sense to you" or "you know better"

I've had amsoil in my car for the past 125k miles, with a once per year change. Engine still running strong.

Yes, lab tests on my own car. I can't speak for everyone because I never tested their car.

Also, you can't say that because your engine is "running strong", that your oil changes are fine. My old 1985 cavalier never had it's oil changed in the three years I owned it and it was "running strong" until it completely siezed up out of the blue.

 

[Zorba]

Originally posted by: Gillbot

Originally posted by: SoulAssassin

Originally posted by: Gillbot
Personally, I think amsoil is overrated and their mileage claims are laughable at best.

25K between changes is rather crazy. I do it once a year in my Jeep which works out to every 8-10k. Probably could go longer but I abuse the hell out of it.

It's a complete joke anytime a manufacturer puts an arbitrary number on an oil change interval. You need to consider the environment and service duty of the vehicle first before you can determine a proper oil change interval. The Z28 in my sig is LUCKY to get 3k miles on it's fully synthetic oil due to fuel dilution, but then again the Z28 sees severe service duty at the track often.

Furthermore, while the oil may be able to maintain lubricity for 10k+, the oil filter probably cannot. I bet 99% of the people who buy into this 10 and 25k garbage toss this oil in thinking it's a cure-all and they never change their filter until they change the oil.

This thread is about Gear Oil for differentials, not engine oil.

 

[Gillbot]

Originally posted by: CupCak3

Originally posted by: SoulAssassin
I run Amsoil...I would either do that or Redline or Royal Purple. All good stuff. I really should put the cheap crap in because this is in my Jeep and I end up having to change the fluids every 6 months after doing deep water crossings.

+1 for amsoil

Originally posted by: Gillbot
Personally, I think amsoil is overrated and their mileage claims are laughable at best.

Originally posted by: Zorba
This thread is about Gear Oil for differentials, not engine oil.

Still applies.

 

[Zorba]

Originally posted by: Gillbot

Originally posted by: CupCak3

Originally posted by: SoulAssassin
I run Amsoil...I would either do that or Redline or Royal Purple. All good stuff. I really should put the cheap crap in because this is in my Jeep and I end up having to change the fluids every 6 months after doing deep water crossings.

+1 for amsoil

Originally posted by: Gillbot
Personally, I think amsoil is overrated and their mileage claims are laughable at best.

Originally posted by: Zorba
This thread is about Gear Oil for differentials, not engine oil.

Still applies.

I was referring to this part:

Furthermore, while the oil may be able to maintain lubricity for 10k+, the oil filter probably cannot. I bet 99% of the people who buy into this 10 and 25k garbage toss this oil in thinking it's a cure-all and they never change their filter until they change the oil.

Amsoil does seem very proud of itself.

 

[SoulAssassin]

Originally posted by: Zorba

Originally posted by: Gillbot

Originally posted by: SoulAssassin

Originally posted by: Gillbot
Personally, I think amsoil is overrated and their mileage claims are laughable at best.

25K between changes is rather crazy. I do it once a year in my Jeep which works out to every 8-10k. Probably could go longer but I abuse the hell out of it.

It's a complete joke anytime a manufacturer puts an arbitrary number on an oil change interval. You need to consider the environment and service duty of the vehicle first before you can determine a proper oil change interval. The Z28 in my sig is LUCKY to get 3k miles on it's fully synthetic oil due to fuel dilution, but then again the Z28 sees severe service duty at the track often.

Furthermore, while the oil may be able to maintain lubricity for 10k+, the oil filter probably cannot. I bet 99% of the people who buy into this 10 and 25k garbage toss this oil in thinking it's a cure-all and they never change their filter until they change the oil.

This thread is about Gear Oil for differentials, not engine oil.

Amsoil makes gear oil as well which is what I was originally referring to. I've got half a case of 75W-90 in the garage right now.

 

[Gillbot]

Originally posted by: Zorba

Originally posted by: Gillbot

Originally posted by: CupCak3

Originally posted by: SoulAssassin
I run Amsoil...I would either do that or Redline or Royal Purple. All good stuff. I really should put the cheap crap in because this is in my Jeep and I end up having to change the fluids every 6 months after doing deep water crossings.

+1 for amsoil

Originally posted by: Gillbot
Personally, I think amsoil is overrated and their mileage claims are laughable at best.

Originally posted by: Zorba
This thread is about Gear Oil for differentials, not engine oil.

Still applies.

I was referring to this part:

Furthermore, while the oil may be able to maintain lubricity for 10k+, the oil filter probably cannot. I bet 99% of the people who buy into this 10 and 25k garbage toss this oil in thinking it's a cure-all and they never change their filter until they change the oil.

Amsoil does seem very proud of itself.

I hate the fact that they purposefully misrepresent their product to unknowing consumers. Printing gigantic mileage claims with extremely small fine print on the back is the norm now though. I guess if consumers don't read the label, it's their fault.

 

[radioouman]

I have limited experience with these, but I'll give you my anecdotal first hand experience.

I have had several Chrysler cars that required either ATF+3 or ATF+4. ATF+3 always frustrated me because the transmission would shift great for about 15,000 miles and then it would gradually deteriorate. ATF+4 is a full synthetic and when I run it in the cars that needed ATF+3, the shift quality is maintained far longer. (Thus I assume that the ATF+3 breaks down faster.)

Two of these Chryslers are Dodge Dakotas, one of which has a limited slip rear differential and the other doesn't. The one with limited slip requires a friction modifier with 80W-90. But synthetic gear lubes meet the requirement for the limit slip diff.

 

[Demon-Xanth]

I ended up putting Redline MTL in my transmission (NV3500) and Richmond Gear lube in my rear end (9.25" LSD) when I changed out the fluids at 50k. I figure the fluids ran me $50 and I don't change them very often and they already had the correct additives mixed in. I'm not sure if I'm going to change them again at 100k or just let them ride a bit longer.