I want to double check with you to make sure which transmission fluid. Soon will drain motor oil. I do not plan to drain transmission fluid but will replace transmission spin filter. I need to know which fluid I need to pour in the Allison spin filter. I have a manual duramax book here with me. It says dexron VI automatic transmission fluid. For areas where ambient temperatures are below -40 f (-40 c) use synthetic transmission fluid approved to allison transmission - specification TES-295. I was wondering is there a way to know which fluid did GMC put in my truck? I would think maybe Dextron VI.

Dextron VI is the correct answer...

More than likely, it is filled with Dexron VI.

I get my allison spin on filters from the local international dealer. They also have the correct trans fluid. I usually go in and buy two filters and a quart of fluid and it's under 20.00. This is good enough for two changes as it only takes a pint to fill the filter.

You won't loose enough fluid from that puny filter to need replacing the fluid........

I get my allison spin on filters from the local international dealer. They also have the correct trans fluid. I usually go in and buy two filters and a quart of fluid and it's under 20.00. This is good enough for two changes as it only takes a pint to fill the filter.

Today I went over to Allison service dept. They do not sell quart. They sell only synthetic fluid in a gallon. I only need regular Dextron-VI ATF.

Dextron VI is the correct answer...

More than likely, it is filled with Dexron VI.

Whew! I thought so. Carquest salesperson said use carquest brand and suggested Dexron-VI synthetic fluid. I told him I prefer name brand and I want ATF. They did not have in stock so I went to Pep Boy auto parts. I bought one quart of Pennzoil Dexron-VI ATF. On the back of the container has a label "fully approved to meet GMN 10060, and is suitable to be used where Dexron IIH, III and IIE. I hope this is the right one. Many Thanks!

When in doubt...follow the manual.

transynd

Thought I would tell you this. I was told that when you replace a new spin filter, make sure the filter turns not 3/4 but one full turn due to high pressure from the transmission.