Does atf change cause a temporary drop on mpg?

Just wondering cos mine was done at 40k km mark by the dealer. it feels as though mpg has dropped slightly. used to be able to hit 36km/l on the work commute on occasion. after the change struggled to hit >30. now 3 months later it’s around 30-33km/l. we’re at the 48k km mark. hopefully it keeps improving. i didn’t check what atf was used, hoping that it was toyota ws and not a cheap aftermarket.

 

thanks Alan, yes it was auto trans fluid and done when i brought it in for routine oil change. i think the workshop scheduled it at this odd 40k just so that they can earn extra on the markup and labor. unfortunately my car is a jdm import so the local toyota here will refuse to service it so that people are forced to buy the car (official export version) from them instead. i have no choice but to get my warranty and routine service from a 3rd party workshop instead. thus they can claim that if i do not follow their schedule it will void our warranty agreement.

tyres are fine. i keep them in the high 280kpas as reported by the tpms

 

went back and checked the receipt. apparently they used 3.5l of Aisin AFW+ .

spec sheet is here http://www.exedy.com.au/assets/file/AISIN_Fully_Synthetic_AFW_Multi_Product_Datasheet.pdf and promotion poster is here http://www.aisinaftermarket.jp/en/products/atf/images/atf_a2_CFEx_AFW+.pdf

did some wikipedia on this company. part owned by Toyota, they apparently were the developer of the gen1 and gen2 prius transmissions !?!

i think this atf checks out for the prius. afw+ is claimed compatible for toyota ws-the prius atf. the poster also recommends 40k or 2 years change which explains the odd schedule. i think my drop in mpg might also be due to other factors as well-like a change in commute route all else being equal.

 

just wish to update that i’m getting back to my normal mpg performance. about 4 months after the atf change. phew s!