Synth Fluid "Debate"

[Rotorflyr]

Ok,
Read on a thread on another forum (non SVX), a well let's call it a "Debate" on how after a certin milage, (IIRC 120k+ or so) if you hadn't changed to Synth fluids (engine, tranny etc....) it wasn't worth doing, nor was it (in some case's) safe to do so......
Any thought's/feelings/opinions (facts?) on this? (in the case of the SVX)

[lee]

it's a fact that synthetics have a greater cleaning (detergent) effect than dino fluids. What this means for older vehicles is that a layer of hardened "crud" behind seals can be cleaned off, then leaks appear. There are internal seals in an automatic transmission that once start leaking can result in damage ...this is along the same lines as people who get a cleaning/flush done on a hi-mileage transmission then incur failure not too many miles later.

In my opinion, use a proper conditioning and cleaning fluid before the switch and some/all of the problem may be avoided. www.autorx.com and www.autorx.net represents one brand of engine and transmission conditioners I've seen good reviews for - there are others too.

other than the seal issue, it's my opinion that synthetics bring the same level of benefit to old as to new engines & transmissions, i.e., greater tolerance to heat and resistance to shearing of the molecular chain.

I also think that a cost/benefit ratio shows dino oils to be better for the average user (non-racer, non-severe-duty vehicle, etc).

Standard Fluid or motor oil lubricates.

Additives do not lubricate. They help oil to break down more slowly.

The less oil you have, the less lubrication.

The more additives, the longer the blend lasts.

My car has had Mobile1 Full Synthetic since I purchased it.

I use standard ATF and Diff oil.

To my understanding, if you have used regular motor oil for a long period of time (>50K mi) it is actually a bad idea to use synthetics or fluids that have alot of detergents in them. Here's why: there is a "sludge" that builds up in your engine over the years. This stuff is yucky and full of nasty sediment. When you drain your oil and add normal oil the sediment is not disturbed. When you add detergents or synthetic motor oil this "sludge" starts to be circulated through your engine. This can cause more problems than good.

I thought that the SVX called for synthetic oil anyway. Am I wrong?

I also read a TSB about transmission fluid and differential fluid additives. It said that Subaru does not reccomend you use anything except standard OEM type fluids. The systems were not designed for any other viscosity. Allthough, adding these will not void the warranty. (who has a factory warranty today anyways?)

While we are on the subject of fluids in our beautiful Subaru's, I would like to advise AGAINST having your transmission flushed and filled. I had this performed about 5 weeks ago and my Subie rests on a lift as you are reading this. She'll still move but I'm not going to drive her untill she's a 4 spd again. (I still have 1st & 2nd gears) The transmission wont engage 3rd or 4th gears. I'll git er done though!

Good luck out there!

-Elliot

[LarryIII]

I have converted all our cars to synthetic engine oil (Mobil 1) and have had no problems. I converted all our SVX transmissions to synthetic ATF.
The '97 OB & SVX (bought new) had their engine oil changed to synth. from their first oil change. The '97 SVX had it's ATF changed to Red Line synth. at the 6 month mark. I now has Mobil 1 ATF.

The '92 and '94 pearlies (bought used) had their engine oil changed to synth. at 80K when I got these cars. At the same time, I changed the ATF to synth. and did so at each oil change for the first year of ownership. Both trannys dripped for about a year then stopped. I have had no problems with the trannys. to date. The '92 now has 133k on it. It has developed either and oil pump or front seal oil leak (drip) it's about 1/2 quart over 3-4K miles. I'll have to check into this soon.
I did not want to do a tranny flush on older (80K) trannys.

I'm happy with the results so far.

[dcarrb]

Originally posted by SEA Sleeper
I thought that the SVX called for synthetic oil anyway. Am I wrong?

I'm fairly certain there's no such preference stated in the owner's manual or maintenance schedule.


dcb

Originally posted by LarryIII
.The '92 and '94 pearlies (bought used) had their engine oil changed to synth. at 80K when I got these cars. At the same time, I changed the ATF to synth.

How do you effectivly drain all of the old fluid out of the tourque converter and lines when changing to synthetic ATF w/o first flushing w/ synthetic? I understand why you wouldnt want to flush a higher mileage tranny; I had a flush done on my higher mileage transmission (112K) about 5 weeks ago. Now I have no third or 4ht gear. Enought about that though. I am interested to know how you would be able to switch to synthetic ATF w/o flushing the transmission?

[Earthworm]

Just do a gradual conversion to synthetic. Eventually you'll be running pure synthetic.

[lee]

Originally posted by SEA Sleeper
How do you effectivly drain all of the old fluid out of the tourque converter and lines when changing to synthetic ATF w/o first flushing w/ synthetic? ...snip.

One way is to drop the fluid line to the cooler and fill at the same rate as it pumps out. An alternate (and safer) way is to do multiple drain & fills. On my car I get about 7 qts (from 10 total - including the torque converter) from each change. The attached graph shows how quickly it would approach 100% change by just drain & refill.

[LarryIII]

Originally posted by SEA Sleeper



How do you effectivly drain all of the old fluid out of the tourque converter and lines when changing to synthetic ATF w/o first flushing w/ synthetic? I understand why you wouldnt want to flush a higher mileage tranny; I had a flush done on my higher mileage transmission (112K) about 5 weeks ago. Now I have no third or 4ht gear. Enought about that though. I am interested to know how you would be able to switch to synthetic ATF w/o flushing the transmission?

You just keep, changing the ATF every oil change (approx. every 3000 mi. )for about a year +. There is always some residual old petroleum based ATF, but after 5-6 changes the amount is miniscule. Now, I change the ATF on all the SVes once per year or about 12-15k miles. After so many synth. ATF changes I would say that the fluid in each tanny is approx. 99% synth. It will never be 100%
This is not cheap but I look at it as inexpensive tranny insurance.


There is an old soldier's adage that if you take care of your weapon (cars included) it will take of you.

Good Luck.