Just a quick question! If I choose to change my own transmission fluid, does that void any warranty with the drivetrain? Thanks!

You can change your own fluids, but maintain all receipts, and document mileage and date done. This way, there is no problem further down the road should an issue occur and proof of maintenance is required

Don't bother with synthetic, it will kill your synchros in short order.

Stick to the dino, or try Uncle Scotty's special brew.

How important are receipts? What is the significance? Can SOA deny a claim because, even though everything LOOKS to be maintained, you don't have receipts to cover the purchases of enough oil and filters? I mean, really, the proof of maintenance is what the parts and fluids look like. The parts don't lie. You can have receipts showing you purchased items, but the proof of installation is in the actual visual inspection of the parts in question. Likewise, just writing it down in a maintenance log is no proof. I'm all for changing your own fluids though!!!

Columbo, the reason for the receipts is to show evidence of the *full history* of maintenance. What parts/fluids are in/on the car currently only reflect the most recent service.

Don't bother with synthetic, it will kill your synchros in short order.
Where did you get that idea? I've been running synthetic for several years and I have no problems. Many others here also run synthetic w/no problems.

Andrew @ Geartech recommends Redline Lightweight Shockproof, a synthetic, for the WRX transmissions and he is highly regarded here as the WRX transmission Guru. OK. Maybe the last part is a little over-the-top but you get my point.

Where did you get that idea? I've been running synthetic for several years and I have no problems. Many others here also run synthetic w/no problems.

Andrew @ Geartech recommends Redline Lightweight Shockproof, a synthetic, for the WRX transmissions and he is highly regarded here as the WRX transmission Guru. OK. Maybe the last part is a little over-the-top but you get my point.


So you have a handful of brands that work as opposed to the majority that destroy.

1. as far as "the parts don't lie" if you're in a situation where you need warranty work done, some part ain't gonna work so good.

2. as far as synth in the trans, synthetic is know to have less friction and that's what syncros rely on. it may be better for the gears themselves, but if your syncros aren't up to the task, you're gonna be grinding and that's not good.

that being said, people seem to have good luck with redline but Many people have had bad experiences with Mobil 1, Royal Purple, Valvoline synth as gear oil.

BTW - the aformentioned scottys coctail is redline with some syncromesh (parrafin based to help syncros) and something else that I can't remember offhand.

Yes, keeping the receipts is to show that the car has been maintained thru out the life of the car. What the fluids currently look like has really no bearing. If you develop sludge in the engine from not changing the oil frequently enough, just because the current fluids look good, that doesnt mean anything.

If you purchase the oils and filters and do it yourself, your best bet is to either keep a log with mileage and date, and/or keep the receipts and write the mileage and date on them that they were changed (not when you bought them)

Trust me, you can tell when someone "fudges" a maintenance record and when they are accurate.

Don't bother with synthetic, it will kill your synchros in short order.

Stick to the dino, or try Uncle Scotty's special brew.


I agree. It seems like the majority of people having problems with their Subaru or EVO tranny's, are ones who were playing around with synthetics. I know it's only anecdotal, but the more I read on Nasioc and EVO.net, the more I'm convinced I'll stay with regular tranny oil.

akira02rex,
I think it is important to point out that the manual requires GL-5 based transmission oil. Some of the suggestions on this site, and even in this thread, don't meet this requirement. So if you decide to run something that does not meet manufacture requirements, you do indeed run the risk of warranty troubles down the road if you ever have the bad fortune of transmission problems.

Also, there is a lot of anecotal evidence that synthetic tranny oil is hard for our synchros to deal with. You should really ask yourself what benefit synthetic is delivering against what risks you are potentially taking. I personally just use any GL-5 from the local auto parts store and change it per the "severe" service schedule. It's as easy as changing oil, the only special tool you need is a long funnel, or a funnel with some tubing attached to the bottom.

OK BACK ON TOPIC, My original question was as follows: Does it void the warranty any way to change my own tranny fluid? I am using the stock fluid that's it!!!

OK BACK ON TOPIC, My original question was as follows: Does it void the warranty any way to change my own tranny fluid? I am using the stock fluid that's it!!!

Didn't Rexygirl answer your question in the first reply?
In case you missed it: your warranty is in not voided by doing maintenance yourself. Just use the required grade parts and fluids, keep receipts and a log.

FWIW, I change my own tranny fluid and had my first gear synchro replaced under warranty. My dealership never asked me about servicing...abuse is the reason most transmission warranty claims are denied.

Just to reiterate, see post #2 and then post #13. Then read this post and repeat if neccesary.

I dont think receipts show anything, other than what you bought to use on the car. It doesnt say if you really used it on your car.

I buy 5 gal jugs at walmart, sometimes I buy the year supply.

At least document it all at mysubaru.com. Dealers document everything there too.

I dont think receipts show anything, other than what you bought to use on the car. It doesnt say if you really used it on your car.

I buy 5 gal jugs at walmart, sometimes I buy the year supply.

At least document it all at mysubaru.com. Dealers document everything there too.

No, actually we don't...that is up to the customer

Changing the fluid yourself should not void the warranty. Plus another vote for the Redline Lightweight Shockproof. I have used it for a few years, and started using it to solve a synchro problem. I have been very happy with it. Also, I have seen Redline fluids for sale at the Annapolis Subaru dealership.

Utilize the mysubaru.com site to keep record of your services/repairs, as it is a great resource.

That's like asking if your warranty is voided if you change your own oil. Just keep receipts, and a log of when, milage, and what you put in.

BTW, I put in 1 qt of synchromesh with the rest castrol hypoy C recently. Been running it for about 1K miles now, and seems to be doing just fine.

Isn't your car pretty highly modified? I'd have thought you'd be more concerned about that than the maintenance. Anyway, I think the answer provided by RexyGirl in the beginning pretty much covers it. I prefer the dealer doing maintenance while it's in warranty anyway since they may pick up on any issues I miss - plus with my CPO Baja - I have the extended service agreement and it may require proof of maintenance.