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Automatic Transmission Servicing

How to avoid some common, and potentially costly, service mistakes.
Friday, July 19, 2013 - 11:56

I own two vehicles that do not have an automatic transaxle dipstick to check the fluid level. One of these vehicles is a General Motors product; the other is a Toyota product. And they are not the exception. Ford also has automatic transmissions without dipsticks as do Chrysler, Mercedes and other OEMs. The lack of a dipstick is no accident; the transmission manufacturer does not want the customer to have access to the fluid. They call it “lifetime fluid,” and it supposedly never needs changing, but it does need to be checked when there is a sign of leakage, if the transmission is having problems or if the transmission was opened for any reason. Some transmissions are so sensitive to improper fluid levels and fluid types that transmission problems or even damage can occur with the slightest under fill or over fill. 

The tube is still there, but you’ll need to order your own dipstick if you want to check the level on this trans.

If your shop is in the business of servicing or repairing automatic transmissions or if you are just performing quick services such as an engine oil change or a transmission fluid flush, you better not tell a customer that their fluid level is "OK" unless you really checked it the proper way. I have taught classes on automatic transmission diagnostics, service and overhaul for 22 years. Most technicians I have had in class (experienced or not) make simple mistakes that cause them to check the fluid improperly.

Checking an automatic transmission's fluid level properly requires four resources; access to the proper service information, up-to-date training, adequate time to perform the fluid level check and access to special tooling if required.

Adventures In Reality
My first vehicle without an automatic transaxle dipstick, a Toyota Highlander Hybrid, was purchased new in 2008. I received free oil changes every 5,000 miles for the first 75,000 miles as part of the purchase, so I had this vehicle serviced at the dealership for the last five years (83000 miles). The green-yellow-red colored multi-inspection check sheets I receive with each service always show all of the fluid levels as being OK. The problem is the fluid level check plugs appear to have never been removed, as evidenced by the factory paint marks on them.

I recently asked a technician from a different Toyota dealership what his dealership does regarding checking transmission fluid levels on vehicles without dipsticks. He said they do not check the fluid level unless there is a sign of leakage. I asked him if they mark the fluid level as "OK" on the multi-point inspection sheet the customer receives, and he said some technicians do. I told him that I thought that was a huge problem and a possible liability for his employer.

This is a GM check plug. Seems easy enough, but if the fluid temperature isn’t right you may actually let fluid out that needs to stay inside!

I suggest that it is a better idea to tell the customer that you did not check the automatic transmission fluid level because of whatever the reason is for that particular vehicle. If a customer's automatic transmission does not have a dipstick, consider selling them a proper fluid level check at an additional cost and time. Isn’t it commonplace to charge more to service some types of vehicles because of the additional expense for fluids, filters or labor? Automatic transmissions without dipsticks are an additional labor issue.

My other vehicle without an automatic transaxle dipstick, a 2002 Chevrolet Cavalier, was purchased three years ago for my teenagers to drive. I have had this vehicle serviced at a local national chain quick lube business.  The multi-inspection check sheets I receive with each service show all of the fluid levels as being "OK." The problem with the 4T45-E is the fluid level cannot be checked properly in this transaxle if the fluid temperature is above 104 degrees Fahrenheit. If you remove the fluid level check plug on this transaxle and the fluid temperature is above 104 degrees, the fluid will have expanded and it will appear to be overfilled and fluid will spill out of the check plug hole. This will actually cause the fluid level to be too low when checked properly.

I asked a technician that works for this national chain quick lube business what they do about checking fluid levels on automatic transmissions without dipsticks. He said unless there is a leak, they also mark the level as "OK" even if they never checked it. He also told me the company was making efforts to address this issue because of the many vehicles that come through their doors without transmission dipsticks.

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