Hi I noticed the mpg has dropped from approx 65mpg to 58mpg. Not sure this will improve over time??

Thanks will give them a call tomorrow.

mpg calculation is based on same temperature and road conditions before and after oil replacement. Last week and this week temperature is approx 15-16 deg C in my region.

A google search on this subject thows up quite a lot of discussion on the various Toyota forums, including a comment from HJ in the Telegraph about possible oil reasons for poor gearchange.

My opinion is, if the box is nice to use cold and still nice to use warm, i wouldn't worry too much about it, manufacturers often change oil specs during the life of cars when gearchange problems rear their heads, hence one dealer sticking to the orignal spec and others suggesting what they have found works better for any particular issues.

A thinner oil might be better for continual cold running, but might be too thin once warm, you say its driving well and that would be my acid test.

Its got fresh oil, thats the important thing, i've never yet changed transmission oils and failed to notice an improvement, i don't buy Gucci gear oils made from unicorn tears i buy 20/25 litre packs from long established suppliers of the correct grade (same as engine oils when on offer), the only difference in feel was when i bought some LSD oil for a particular rear axle, which seemed much thicker and stank horribly.

GL5 tends to be 75w90, but also 80w90 features and in one case, Mannoil 85w140, i bet you'd struggle to tell the difference between a 75/90 and 85/90.

More updates on this oil change saga:

I had reply from Toyota UK, the correct part is LV SAE 75W MT 1 Litre (088581001) API GL-4.

Further quiry into the exact oil been put into the gearbox is 85W/90 GL4 / GL5 (suspect non-Toyota oil as no part number on invoice, just read LS 85W/90 Gear Oil).

I am not happy due to the fact that the action they have done could potentially damage the gearbox (synchromesh/synchronising gears with soft metals).

When I mentioned to the dealer that the oil recommended by the manufacturer is LV SAE 75W MT 1 Litre (088581001) API GL-4. (This is also detailed in the car's handbook). Then the service team changed the story saying the invoice showing the wrong oil description (are they incompetent or lying?). They now claim it is the correct part has been used (i.e. 088581001).

What do you guys think I should do now? Take their words or get another gaarge to replace the oil (I will supply the correct oil this time).

I am also dissapointed the fact that the dealer can get away with it when I paid for the "Toyota FIxed Price Service/Repair" and I didn't get the genuine parts as recommended by the manufacturer and now causes more concern for me to deal with.