Transmission fluid flush, fluid change intervals, etc

dano · Jul 17, 2015

So I was looking for info and people's experiences on Royal Purple TRANS fluid as my Avvy is getting up there in miles. What I found was a lot of discussion on fluids, flushing and service intervals. I wanted to add my $.02 as a 47 year old owner who has owned over 50 vehicles and has worked on hundreds in the last 30+ years.
I have a 2003 North Face Edition 1500 4x4 with 185,000 miles that I bought new. 10k of that is towing various things from relatively light jet skis to trailers with so much firewood on them I really had no business towing them. I am a former GM technician (from the 90's) so I'm not in the game every day anymore but I still turn wrenches on a regular basis as I buy broken vehicles, fix and sell and also work on lots of other people's vehicles. My truck is still going strong, no issues to date. I have the TRANS flushed, yes flushed, every 30k. I am 47 and have never had to take any of my vehicles to a dealership. As a former master tech, I have always been able to figure out any issues on my own thanks to collaboration on fantastic forums like this one. But I do take my vehicles to Jiffy Lube for their $99 TRANS or coolant flushes.

Two things to note:

1). It is extremely important to determine the method and direction of flow that will be used to flush your TRANS. If the shop doesn't know or can't answer you, run away! Flush in direction of normal flow and with low pressure and there should not be any issues. it is possible to flush by yourself by supplying new fluid to the suction line and capturing old fluid as it comes out, but it generally makes a giant mess and if you happen to suck air you're putting the transmission at risk. Back flushing is ALWAYS a bad idea, don't ever listen to anyone who tells you any different, doesn't matter who they are or how many degrees they have. Even if you change the filter immediately after back flushing you have forced dirt out of the filter into the rest of the TRANS by back flushing. High pressure in the wrong areas can blow out seals, yes the TRANS is designed for high pressure but only in the right areas.

2). DON'T listen to manufacturers who say to go 100k on your TRANS fluid!! They are full of crap! 50k is probably too much. Some VW automatics have a sealed fill port, no dipstick to even check the fluid, and they say their fluid is "lifetime", no change required!!! (Just look on Craigslist to see how many used VW's are on their with bad tranny's, I buy them all the time) Manufacturers do this crap for many reasons, increasing repair customers and new sales due to major failures are just the obvious ones. Total ownership costs are projected on new vehicles and a rigorous maintenance schedule increases those costs and makes vehicles less appealing to buyers. Manufacturers go for long intervals on maintenance items to lower those projected costs. Common sense dictates that you keep all of your fluids clean.

Change or flush any time your fluid appearance changes or darkens significantly. If you're planning on keeping your vehicle I'd say every 30k.

Randy · Jul 17, 2015

I've been using Royal Purple in my trans since the first service at around 50,000 miles and about every 50,000 since then, currently at 233,xxx and no issues (knock on wood). I agree do not flush the trans with the high pressure method that back flushes it. Like you said it will dislodge dirt and send it through the trans here you don't what it..

I also have been going to the local oil change shop and have the trans fluid "exchanged", not flushed. I bring my own fluid (Royal Purple) and they disconnect the upper line (leaving the Radiator cooler), put a fitting in it and that goes into the reservoir (dirty side) on the machine. They connect the line coming out (going to the aux cooler) to the clean side of the machine where they put the new fluid. When you start the motor the dirty fluid come out of the trans into the machine, as that happens the new fluid goes into the line at the same pressure and direction. So all your doing is exchanging the old fluid with clean. When that's all done I drop the pan and put in a new filter and it's good to go until the next service.

I'm made my own flush set up using new 5 gal pails with locking lids duplicating what the machine at the shop does. It used air to pressurize the pail with the new fluid to the same as the pressure coming out of the trans and the old fluid will just go into the other sealed pail and it has fittings on it to use air pressure to drain it when done. I had a cruder version a long time ago and it worked good, this one has a few more bells and whistles to make it easier.. Not in the picture but there are safety straps that go around the pressurize pail.

I haven't used the new set up, I will when the next service is due in about 20,000 miles. I just need to put a pressure gauge on the trans line to see what it is at idle so I can duplicate it in the pail.

tblt44 · Jul 26, 2015

each there own , I never flush just change fluid and filter ,install drain plug and drain and refill a few months later.

bkennedy39 · Oct 6, 2015

the shops all want to do a flush.

Some of the real established shops here in okc , that are small, will do the traditional drain, replace , filter, which to me seems better and certainly much cheaper. my 01 chevy truck was never flushed, and I had Castrol synthetic in it, with over 177k before a hail storm totaled it.

TO me it's the easy expensive way out.

PromptCritical · Oct 6, 2015

I just got mine flushed at the dealership. I think the scheduled interval is 50k, but at my last change they said the fluid was looking a bit bad so it needed it early. I bought the parts and had them install the OEM HD tranny cooler so the fluid should last longer next go around.

bkennedy39 · Oct 9, 2015

dano said:
So I was looking for info and people's experiences on Royal Purple TRANS fluid as my Avvy is getting up there in miles. What I found was a lot of discussion on fluids, flushing and service intervals. I wanted to add my $.02 as a 47 year old owner who has owned over 50 vehicles and has worked on hundreds in the last 30+ years.
I have a 2003 North Face Edition 1500 4x4 with 185,000 miles that I bought new. 10k of that is towing various things from relatively light jet skis to trailers with so much firewood on them I really had no business towing them. I am a former GM technician (from the 90's) so I'm not in the game every day anymore but I still turn wrenches on a regular basis as I buy broken vehicles, fix and sell and also work on lots of other people's vehicles. My truck is still going strong, no issues to date. I have the TRANS flushed, yes flushed, every 30k. I am 47 and have never had to take any of my vehicles to a dealership. As a former master tech, I have always been able to figure out any issues on my own thanks to collaboration on fantastic forums like this one. But I do take my vehicles to Jiffy Lube for their $99 TRANS or coolant flushes.

I just changed my 06 LS 2X2, with 127K, and I looked clean 3.8 years ago, everyone in these parts wants to flush, couldn't find a single place that would drop the pan.. Good thing did, the fluid was starting to change color, and the tranny filter was starting to deteriorate. I would recommend Wix, and Valvoline dextron 6 synthetic, as it seems to really work great!

Two things to note:

1). It is extremely important to determine the method and direction of flow that will be used to flush your TRANS. If the shop doesn't know or can't answer you, run away! Flush in direction of normal flow and with low pressure and there should not be any issues. it is possible to flush by yourself by supplying new fluid to the suction line and capturing old fluid as it comes out, but it generally makes a giant mess and if you happen to suck air you're putting the transmission at risk. Back flushing is ALWAYS a bad idea, don't ever listen to anyone who tells you any different, doesn't matter who they are or how many degrees they have. Even if you change the filter immediately after back flushing you have forced dirt out of the filter into the rest of the TRANS by back flushing. High pressure in the wrong areas can blow out seals, yes the TRANS is designed for high pressure but only in the right areas.

2). DON'T listen to manufacturers who say to go 100k on your TRANS fluid!! They are full of crap! 50k is probably too much. Some VW automatics have a sealed fill port, no dipstick to even check the fluid, and they say their fluid is "lifetime", no change required!!! (Just look on Craigslist to see how many used VW's are on their with bad tranny's, I buy them all the time) Manufacturers do this crap for many reasons, increasing repair customers and new sales due to major failures are just the obvious ones. Total ownership costs are projected on new vehicles and a rigorous maintenance schedule increases those costs and makes vehicles less appealing to buyers. Manufacturers go for long intervals on maintenance items to lower those projected costs. Common sense dictates that you keep all of your fluids clean.

Change or flush any time your fluid appearance changes or darkens significantly. If you're planning on keeping your vehicle I'd say every 30k.

bkennedy39 · Oct 9, 2015

PromptCritical said:
I just got mine flushed at the dealership. I think the scheduled interval is 50k, but at my last change they said the fluid was looking a bit bad so it needed it early. I bought the parts and had them install the OEM HD tranny cooler so the fluid should last longer next go around.

Change the filter , as over time it wears out, I just experienced it on my 06 Avalanche It had never been changed, only flushed and there was foam debris in the bottom from the 9 year old filter. Use a wix tranny filter, and Valvoline dexron 6 synthetic.

PromptCritical · Oct 9, 2015

bkennedy39 said:
Change the filter , as over time it wears out, I just experienced it on my 06 Avalanche It had never been changed, only flushed and there was foam debris in the bottom from the 9 year old filter. Use a wix tranny filter, and Valvoline dexron 6 synthetic.

They did, or at least they put it on the receipt. Just like an oil change: Change the fluid, change the filter. Even if you don't flush.

Randy · Oct 9, 2015

I would guess most need to service at 50,000 miles, 100,000 miles to me is to long.. Cheap insurance IMO..

From the 2002 owners manual...

Scheduled Service

50,000 Miles (83 000 km)

Change automatic transmission fluid and filter if the vehicle is mainly driven
under one or more of these conditions:

? In heavy city traffic where the outside temperature regularly reaches
90F (32C) or higher.
? In hilly or mountainous terrain.
? When doing frequent trailer towing.
? Uses such as found in taxi, police or delivery service.

If you do not use your vehicle under any of these conditions, change the fluid
and filter at 100,000 miles (166 000 km).

- Change transfer case fluid.

Transmission fluid flush, fluid change intervals, etc

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