Mixing Regular And Synthetic Tranny Fluid? 6.0

[Chevyjet52]

I'm getting ready to service the transmission in my truck, it's a 2001 1500HD with the 4L80E tranny. I had it about 18 months. I have no clue what type of fluid is in the tranny, I'd like to use synthetic. My question is: Is it ok to mix regular trans fluid with synthetic since a filter and fluid change still leaves a lot of the old fluid in the converter?

 

I do use the truck for towing and operate near it's max tow rating.

 

Thanks.

[Stevens03]

Yes, you can mix it... I believe on the bottle, it should say it's ok too.

 

Steven

[dsmazz]

It is OK to mix dino and synthetic engine oils. I myself would not do it. You can purge the torque converter of old fluid. That's where the remainder of the fluid is after dropping the pan. If you go to Amsoil's Web site, they have a TSB you can download that explains how to purge the torque converter. Or, I've taken the time to upload it here for you.

ATF_and_Filter_Change_Procedures.pdf

ATF_and_Filter_Change_Procedures.pdf

ATF_and_Filter_Change_Procedures.pdf

ATF_and_Filter_Change_Procedures.pdf

[markw8]

Nothing bad will happen if you mix them

 

Mark

[Chevyjet52]

Thanks everyone!!!

 

I feel much better now.

 

I'm not sure I'm up to unhooking the cooler lines to drain the converter, with my luck i'll spray tranny fluid up and down the driveway & all over the truck..... Thanks for the PDF though!!!

[plowking]

How many miles on the truck? My son-in-law works at a tire, battery,alignment shop. They do trannie flushes hooked to a machine,they don't like doing trannies over 100 thousand miles,if it is there first flush,the cleansing of the transmission and new fluid can cause problems. Did you have any info of previous maintence from last owner? I get my vehicles transmissions done at recommended intervals. The new vehicles now take Dextron Six,a full synthetic fluid. plowking

[green 788]

A 1500 HD with a 4L80?

 

Do you mean 2500? Or am I needing some educating... :o

 

Dan

[Black02Silverado]

No issues at all with mixing synthetic with non synthetic ATF. Over time if you keep changing it out you will switch over to synthetic. It is a slower and less expensive way of doing it.

 

Mazz, thanks for posting the PDF.

[svensk]

A 1500 HD with a 4L80?

 

Do you mean 2500? Or am I needing some educating... :o

 

Dan

1500HD's were a 2500LD. 6.0L/4l80e etc... Just had a badge on the side that said 1500HD.

[Z45]

I agree, mixing them is not likely cause any problem but is it worth it? Sort of like mixing top shelf booze with rot gut and expecting it to still taste like top shelf.

 

The only concern is that is you weaken the new fluid by adding it to the old fluid. Not knowing how long the previous ATF was in there you may not actually accomplish what you want, just have a mixture of old fluid and new fluid.

 

Its relatively easy to purge the complete system, my local trans shop can do that in less than 45 min. including R&R of the filter.

 

Just something to think about.