Help me choose a trans fluid schedule

[Patman]

Here is my situation. I bought my 95 Firebird Formula (which has the 275hp LT1 engine) used in October 2001, and at 57k I had the auto transmission fluid completely flushed, but they didn't have the filter for it in stock, so I kept the original one in there.

This week, I went to a GM dealer and had them do the conventional transmission fluid service, where they drop the pan, put in a new filter, and then refill. So I got about 5 quarts of fresh fluid, while the total system capacity is probably somewhere around 12qts I believe. My car now has 83k on it.

I'm trying to figure out what I should do for future trans service now. Should I alternate the service, meaning one year get the full flush and then the following year do the pan drop/filter change? Or should I just do the pan drop/filter change every year?

Or am I changing the fluid too much? I drive mostly highway, although I also get stuck in a lot of stop and go traffic too, so I'm sure I'm heating up the transmission fluid quite a bit. I drive about 18k a year, and do a lot of hard driving too (full throttle every chance I get, plus drag racing once a month in the warm months)

[ May 07, 2003, 01:47 PM: Message edited by: Patman ]

 

[MolaKule]

Patman,

With your ocasional racing, I would do the "pan drop/filter change every year."

18k is about half the service change schedule for the average driven car.

It would be intersting to see your ATF UOA results on a 1 year oil.

 

[Patman]

How would I go about taking a sample of this fluid if I decide to do a UTOA on it next year? I guess I'd have to invest in a sucker pump to get the fluid up through the dipstick wouldn't I?

 

[msparks]

quote:

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Originally posted by Patman:
How would I go about taking a sample of this fluid if I decide to do a UTOA on it next year? I guess I'd have to invest in a sucker pump to get the fluid up through the dipstick wouldn't I?

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Come on Pat, don't you know that every Oil Nut has a sucker device(vampire) in their garage. Heck they are only $25. You can even use it to impress your friends. I show them my sucker all the time

 

[JohnBrowning]

Patman if it is synthetic then I would not hessitate to follow the factory service spec. If it is non-synthetic I like to drop the pan every 12,000 and change the filter ever 24,000. I have never used a flush symstem as I have never needed to. My latest used car is going to get flushed. Flushing only helps if you have a neglected transmission. If you stay ahead of oxidation then this should never be a problem. My wifes new truck has two filter one on the intake side and one on the return from the cooler. I droped the pan and changed the filter's and 7 quarts of fluid with synthetic. I will do this again soon 30,000 unless the UOA comes back bad. I figure buy staying ahead of oxidation and continiously repalce the semi-synthetic OEM fluid with true synthetic I should be able to eleminate oxidation related problems. I am also going to intall a drain plug so I can simply drain the lower unit ATF out and refill when ever I want to with out droping the pan. My Moms Toyota Tundra requires you to drain the lower sump and refill every 18,000 miles. It does not have a user serviceable filter just a mesh screen. It does have a built in drain plug though.

 

[Patman]

quote:

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Originally posted by JohnBrowning:
Patman if it is synthetic then I would not hessitate to follow the factory service spec.

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Nope, not synthetic, just conventional Dexron III. The GM dealers charge too much $$$ for synthetic trans fluid, plus many f-body experts claim the 4L60E trans does not like synthetic (specifically, it's torque convertor does not like it)

 

[wtd]

With the hard driving you say you do, I would change it once a year with just a pan drop and filter replacement. The fluid should be able to handle a year fine. The 4L60E transmissions are not particularly strong, especially in truck applications under towing conditions and thats why I drain and refill my transmission fluid about every 6,000 miles on my 98 truck with the 4L60E.

 

[Chris 2421]

I would drop the pan and just do a fluid/filter change every 15K.This is the schedule I use on my street vehicles,and on my drag race car,it gets a change at the beginning of every race season

 

[Patman]

Thanks for the input everyone! I will get the GM dealer to do the pandrop/filter swap once per year.

 

[got boost?]

just an fyi, I have a '94 caprice that has 270,000 miles on it (original trans). I've done nothing but follow the recommended schedule and have the dealer flush the transmission every 100,000 miles. the filter was not changed until my last flush. I think doing it yearly is a huge waste of money. instead I'd recommend putting that amount of money (likely ~$100) in the bank every year and follow the manual. the 4l60e is a very tough car transmission. I have towed with my car btw.

 

[Patman]

The 4L60E does not have a durable history in the f-body though. I know many guys who have blown them up, although admittedly most of them (but not all) had much more power than stock. The more I look at it, given my drag racing, hard street driving, and the bad traffic I see, yearly changes are probably not overkill at all.

 

[VaderSS]

Jon Moss, the father of the '94-96 Impala SS, said that 2 things, more than any other, kill 4L60es.

1; Shift points in excess of 6000 rpm.

2; Drag tires.

The transmission was not designed for high RPM shifts.

As long as the excess power has some where to go, ie; up in tire smoke, it should not hurt the transmission, within reason.

 

[got boost?]

quote:

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Originally posted by Patman:
The 4L60E does not have a durable history in the f-body though. I know many guys who have blown them up, although admittedly most of them (but not all) had much more power than stock. The more I look at it, given my drag racing, hard street driving, and the bad traffic I see, yearly changes are probably not overkill at all.

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yeah, I don't know about that, at stock power levels the 4l60e IS a VERY durable transmission. the 700r4 upon which it is based was not reliable when it was introduced, and I think too many people confuse the two. btw the impala ss/caprice should be harder on the transmission than the f-boby (torquier iron head engine, much heavier, and possibly towing). if you take the money you would have blown doing the unnecessary fluid changes, you'll be able offset the cost of replacing the transmission if ever needed (used 4l60e's go for wrenching on cars, if you take that car to the track often, it is much more likely that you will do severe mechanical damage to it well before any wear damage could possibly occur. racing your driver is never a good idea in my experience.

 

[Patman]

Since my LT1 will likely remain close to stock and I won't be doing higher than the stock 5700rpm shift points, hopefully it'll live long enough for me to get back into another LS1 f-body (which if my finances agree, will be probably 3 years I figure)