Transmission fluid- drop and drain or flush?

spikesputnik · May 6, 2014

Been off of the site for a while because my truck ceased to be my daily driver for the last few years, and I'd been doing time in my Civic....

But now at about 60K miles, it is being used almost exclusively for towing my boat (now that I've gotten divorced and found a new family to go boating with

Loaded boat and trailer total weight around 5000#. Silverado 5.3, 4l60, 3.43 gears, HD trailering pkg.

So now that I'm looking forward to a long summer of towing, my attention has turned to transmission maintenance and trying to avoid 4l60-osis.... Seems there are two camps- the drop and drain advocates, and the get it flushed fans.

What is the consensus for mine at this juncture? Get it flushed, or just a drain and filter? I won't be doing it either way, just looking for feedback.

Thx!

PS- yes I use the un-tuned "tow mode" when trailering, but sometimes I forget to hit the button for a few miles LOL

00Silverado4x4 · May 6, 2014

I personally haven't done either on my truck. At 50k miles I had the dealership take care of it before I drove 6300 miles from Alaska to Georgia (scenic route). Now I'm at 120k miles and I think I am just going to do the pan drop, filter change and refill method.

kstruckcountry · May 6, 2014

Mine gets the pan dropped, filter changed, then refilled yearly. If you get in the habit of doing it every year most of the fluid will be very new and you'll be sure to have a fresh filter.

txab · May 6, 2014

Pan drop w/filter.

gmtech4 · May 7, 2014

pan drop & filter ,,,

flush only flushes cash from wallet ,,,,

spikesputnik · May 7, 2014

Thanks guys.

I might be just a little paranoid, or maybe rightfully so considering I had Blackbear do a tranny tune (also) back in 2009. In regular "tuned" it shifts as intended- much quicker and with more authority and I like it. Not that I hammer it (well, very rarely I can't resist..) but every shift is more solid for sure . But I don't know if this in itself would degrade my fluid quicker than average? Of the 50k miles it has on it, probably 48 of them were not towing, and of the 2000 while towing, 1900 were in tow mode FWIW.

Does any of this make a difference?

gmtech4 · May 7, 2014

Thanks guys.

I might be just a little paranoid, or maybe rightfully so considering I had Blackbear do a tranny tune (also) back in 2009. In regular "tuned" it shifts as intended- much quicker and with more authority and I like it. Not that I hammer it (well, very rarely I can't resist..) but every shift is more solid for sure . But I don't know if this in itself would degrade my fluid quicker than average? Of the 50k miles it has on it, probably 48 of them were not towing, and of the 2000 while towing, 1900 were in tow mode FWIW.

Does any of this make a difference?

no

spikesputnik · May 15, 2014

So I had the local shop do a drop drain and filter. I didn't think to ask what kind of fluid they used, but I'm assuming it is different in some way. Seems the tranny shifts a fair amount softer than before, which is ok as it seemed to be getting a little "slammier" recently when not in tow mode and I stay in the throttle a bit. I know some of this firm shifting was due to the tune and which was fine by me, but after the service there is definitely a different feel about the shifts. Not sloppy loose like stock, just not "Bam- you just shifted MFer" either. Bam was worrying me a bit.

Could my stock 5 year old/60k mile fluid have lost some of it's"compressibility", or might the new fluid be inherently "spongier"?? They did say that the fluid looked and smelled fine. Thought about sending a sample to Blackstone, but not even sure if they analyze it like engine oil

sdeeter19555 · June 17, 2014

This is fairly normal...I change the trans fluid in all my Subarus yearly, and it makes a notable difference even using the OE (read: dealer-only) ATF (ie. changing OE ATF with OE ATF). Likely the old ATF was dirty and/or sheared, and/or because of the fresh additives or different additives in the replacement ATF...it doesn't take much to make the feel different.

ATF is not any different than any other automotive lubricant, they get worn out and dirty.