Originally Posted by meilers

Thanks for the excellent post. However, I'd like to add the following:

Be VERY CAREFUL what engine coolant you use -- it must be completely safe for ALUMINUM ENGINES specifically. There are a few low-cost brands out there (Peak, for one) that contain silicates which can degrade an aluminum radiator and even cause engine block wear. Both my dealer and their lead shop mechanic said WRX models in particular should use the factory Subaru fluid (which they sell in gallong jugs as well) and nothing else, because of this danger. Normally I would be skeptical, but the mechanic pointed out that they could actually make more money selling a brand-name fluid to customers -- they would just rather take the loss and avoid replacing radiators under warranty

For the record, I run factory subaru coolant (which is premixed 50/50 with water) + 1 jug of distilled ionized water + 1 bottle of Redline Water Wetter.

Originally Posted by supertek75

I just noticed today that my coolant is running low. Can I just go to a Subaru dealership and purchase a jug of their coolant solution and pour it directly into the coolant tank, or do I have to do a whole flush of my system and pour in the Subaru coolant solutin + the jug of distilled water and possibly the bottle of Redline Water Weter? I know that this is totally a noob's question, but how else are noobs to learn if they don't ask.

Originally Posted by Tinkerbelbarbie

Any one have any comments on using amsoil? I've always preferred it in my sports cars but now I have a new Baja and don't know what to do with it (except maybe sell it).

Thanks!

Originally Posted by BAN SUVS

This post was a reply I made in the transmission forum, but since it covered most all fluids in the car I felt it was worth sticking here. Please post your additional comments and recommendations, but post a WHY with your WHAT. One-liners like "I use Marvel Mystery Oil in my gearbox" will be removed, as well as get you laughed at. Keep it on-topic and informative. This isn't a poll.


Here's my personal fluid recommendations. They aren't the only solution, others will post different choices, but there is no "one" right answer in this case.

Engine oil: 5w30 full synthetic in colder climates. I usually use Mobil 1, but any full synthetic will do. Other favorites are Redline, Neo, Motul, Royal Purple, etc.

Gearbox: Synchro care is critical. There is much debate about what is good for the gearbox. I recently had 75w90 Royal Purple added when I changed my clutch and flywheel, and I don't think it's good for our gearboxes. This is because it is too slick- the synchros can't grab and this helps cause grinding. I will be switching to 75w90NS Redline or Neo 75w90 RHD when I install my 6MT, as these have what are called "friction modifiers" which help the synchros to work faster. Others will say to simply use the factory fluid, but nobody seems to have a certain grasp on exactly what it is or where to get it. Most dealers simply use plain 75w90 dino gear oil for their changes. Yet another option (bet you thought you were just gonna get some real quick answers for you to run to the auto parts store with, huh? ) is to try a 'cocktail' of different oils, usually including dino oil or what is known as GM Synchromesh. Before you settle on what to get, do a lot of searching and reading and decide on what you want to do for your own reasons. Gear oil is a compromise- choose according to what you think is most important. Again, I will be going with a synthetic 75w90 with limited slip additive. Your RS has a limited slip rear diff, so use the same stuff you put in the gearbox.

Coolant: Use whatever you want, as long as you flush out the old stuff entirely. Rather than running a 50/50 mix, try going with about 65% water/ 35% coolant. The coolant is there to not freeze and not boil- water is the best heat exchanger. I also recommend using a product like Redline Water Wetter. The car will run cooler with no other mods.

Brake fluid: I use ATE SuperBlue Racing, but like engine oil, any full synthetic DOT 4 or DOT 5.1 fluid from a name brand will do. Everyone has their favorite. Avoid DOT 5 fluids if you like to drive hard.

Clutch: Same as brake fluid. Shouldn't need to be changed, but bleeding it wouldn't hurt. Bleeding it, however, will require a refill so it might as well be flushed.

Boost fluid: Just kidding.

Cheers,
Kevin

Originally Posted by ej20boost

i replaced the trans fluid with royal purple trans oil in my '03 wrx 5MT. it doesnt seem to grind. i dont know, its been pretty smooth for me(no grinding for a week and a half). when did it start grinding? right after you replaced it?