Use the Subaru oil filter, for flushing I found the best results out of the Wynns product, but I guess you will have to put it around 300 miles before oil change. It restores your engine from inside to "snow white" condition. after oil change, no additives ! tranny flush = NEVER IN YOUR LIFE!!!! just change the tranny filter !! but never a flush, because all the debris will will damage the inside of your tranny instead of depositing in the bottom. for the oil, use full synthetic oil, I am running on the castrol 10w-60, it is the best in the market (over here) it costs very much, but I run on it for 8000 miles before change. it's expensive (quart = 10$) but I run on it more than standard oil, secures my engine (less friction) and more durability. you can use cheaper sysnthetic oils running at 10W-30, 10W-40 or 15W-50, but I recommend the 10W-60 (in the summertime) and the 0W-50 (in the wintertime). hope I helped

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Svxash: Yes, IMHO Auto-Rx works! Just do a Search on this topic and you should find some interesting info. I have used it in the SVX, both Mercedes, the truck and my ZX-11. Engines and transmissions.

Apply as per the instructions. Cutting open a filter can really be an eye-opener and make a believer out of you..

Re: HM, synthetic (&/or semi-synthetic) or Dino?????

In the end it all depends upon two things: the condition & cleanliness of your engine to begin with, what kind of time & $ you wish to spend (another way to catagorized the OCI). I get my oil & filter changed for free at the dealership every 3,000 miles. I drive the SVX for a couple hundred miles and drain & refil with Chevron Supreme because I don't like the 5W-30 they use.

If your engine is clean to begin with, doesn't consume oil, is not leaking any major oil through seals or gaskets, regular 3,000 mile OCI's with a high quality dino such as Chevron Supreme 10W-30 (which I routinely buy for a net cost of $0.59 per quart) will work excelently. It is a wonderful oil. Costs me $3.54 every 3K. The oil ALWAYS looks clear, very little darkening if any. Zero oil needed between change.

If you have some rotating seal issues (as in "major leaks") an Auto-Rx treatment may well work for you. No product can replace missing seal or gasket material, and cracked seals and gaskets will leak until replaced. I just had the 120K service done which included timing belt, resealing all the seals in the front of the engine (cam, crank, oil pump,etc.), new water pump. I can still see a very minor amount of oil coming from the valve cover gasket areas. Drops forming. Insignificant, IMHO vs. even the parts cost of replacing valve cover gaskets, much less the labor involved.

HM oils have their place in a worn (read as "consuming a lot of oil") engine. They are usually a semi-synthetic blend to begin with... I would personally add a couple quarts of 100% synthetic to 4 quarts of the same brand dino resulting in a 33% mix. The semi's from the manufacturers are typically less than 20% synthetic.

In a worn engine I would 1st try a HDEO like 15W-40 Pennzoil LongLife or Delo 400 and see what happened regarding consumption, leaks, etc. These oils are VERY good at cleaning up a dirty or sludged engine.

100% synthetic oils ARE better than plain old dino oils. They had better be as they cost a lost more. They can be left in for longer intervals, have higher resistance to breakdown, etc. If you go for oil analysis, bypass filtration, etc., then extended drain intervals are a realistic option with 100% synthetics.

If you have oil leaks, the synthetics can exascerbate the problems, though.

Cheers!

I use synthetic because it still pours at -40°. You can't squeeze conventional oil out of a container at those temps!

We can see at least -40° in the winter and +40°C in the summer.