Could differences in viscosity (in same spec ATF) cause fluid noise or a humming noise in transmission after oil change?

[AdrianH]

Hi All

I did the 2nd change of ATF in my 05 Toyota Prado and this time round I have a humm - it's a "whooo" sound coming from the transmission. I did a flush and replaced 8 liters of ATF, drove round the block and it was all good. The sound started after about 15 minutes into a long drive. I can feel a vibration that's proportional to the noise and the noise is proportional to revs. The operation of the transmission is not affected at all, it shifts fine in all gears.

I double checked the level the next day and it was fine (yes I did the Toyota method 46 to 56 degrees). I plumbed a clear tube into the cooler system and the fluid has a nice red colour and is clear, no bubbles that indicates fizzing. The pressure was good based on the stiffness of the pipe. I read on a forum about a guy that had issues after an ATF flush and he then added oil and it fixed the issue.

1st time round the car might have had the original Toyota factory WS in it when I changed it to Penrite. This time round (on 260 000km) I decided to use the same brand filter (Ryco) but use Total LV MV ATF (Total energies Oil) and now I have this issue. I always work very cautiously when doing these type of jobs and kept everything clean. Both Penrite and Total has the Toyota WS spec noted. Both fluid changes were done as normal maintenance.

I suspect the noise is coming from the oil pump and not the TC. The noise is there all the time, if it was the TC the sound would change as gears are selected and when lockup occurs. (please correct me on the TC assumption)

I suspect Total ATF has sufficient differences in viscosity to possibly cause fluid noise or cavitation - what do you think?

The Total ATF is thicker (higher Viscosity) that the Penrite and Penrite is a bit thicker than Toyota WS. Toyota WS has the best viscosity index but for this issue the VI isn't relevant.

The other option that could cause this is if something got into the transmission. I checked that the old seal came out with the filter and the new one is correctly fitted.

Please see screenshots of all 3 oils.

Let me know what you think could be causing this?

 

[twX]

The Total fluid you're using is a bit thicker than the other two, and since it's brand new it will not have shear-thinned yet. The fluid is not too thin, and since the problem only happens when the transmission is warm, the oil is not too thick either.

Mixing different fluids can sometimes cause foaming issues. Foaming is difficult to check for since it might settle within a few minutes after you stop the vehicle. You might try another drain and fill with the same fluid to get more of the old fluid out. Or you could switch back to the Toyota fluid.

I'd change the filter too. I doubt it's the problem, but a new filter is cheap and you never know.

 

[Cujet]

Some pumps can create noise due to excess pressure, as the rotors displace and rub. The Ford 6R-80 is known for this. The quick and easy solution is sometimes a lower viscosity fluid.

 

[JavierH19]

Some pumps can create noise due to excess pressure, as the rotors displace and rub. The Ford 6R-80 is known for this. The quick and easy solution is sometimes a lower viscosity fluid.

And they're supposed to relieve the pressure as there will always be an overpressure with the right fluid with high rpm's.

 

[JavierH19]

Are you sure it's not overfilled. You may have filled the cold fluid to the hot fluid level which then rises as the oil heats up. I've heard of overfilled transmissions making a humming kind of noise though I don't exactly know why.

 

[AdrianH]

Thanks for all the advice.

An update…

I replaced 8 liters of oil with Toyota WS oil and the noise is 90% gone! I have ordered 8 more liters and will continue to drain & fill till it’s diluted enough to be silent again. All functions of the transmission is good, no issues.

To me it proves that even within the same oil spec for a vehicle, different brands of oil matter due to having different viscosities and characteristics.

 

[hrv]

Thanks for all the advice.

An update…

I replaced 8 liters of oil with Toyota WS oil and the noise is 90% gone! I have ordered 8 more liters and will continue to drain & fill till it’s diluted enough to be silent again. All functions of the transmission is good, no issues.

To me it proves that even within the same oil spec for a vehicle, different brands of oil matter due to having different viscosities and characteristics.

One reason that I stick to OEM fluid for the tranny or cvt...IMO

 

[Jhemiway23]

One reason that I stick to OEM fluid for the tranny or cvt...IMO

Exactly… not worth the risk for “saving” a few bucks. Pay now or pay later

 

[Jetronic]

Hi All

I did the 2nd change of ATF in my 05 Toyota Prado and this time round I have a humm - it's a "whooo" sound coming from the transmission. I did a flush and replaced 8 liters of ATF, drove round the block and it was all good. The sound started after about 15 minutes into a long drive. I can feel a vibration that's proportional to the noise and the noise is proportional to revs. The operation of the transmission is not affected at all, it shifts fine in all gears.

I double checked the level the next day and it was fine (yes I did the Toyota method 46 to 56 degrees). I plumbed a clear tube into the cooler system and the fluid has a nice red colour and is clear, no bubbles that indicates fizzing. The pressure was good based on the stiffness of the pipe. I read on a forum about a guy that had issues after an ATF flush and he then added oil and it fixed the issue.

1st time round the car might have had the original Toyota factory WS in it when I changed it to Penrite. This time round (on 260 000km) I decided to use the same brand filter (Ryco) but use Total LV MV ATF (Total energies Oil) and now I have this issue. I always work very cautiously when doing these type of jobs and kept everything clean. Both Penrite and Total has the Toyota WS spec noted. Both fluid changes were done as normal maintenance.

I suspect the noise is coming from the oil pump and not the TC. The noise is there all the time, if it was the TC the sound would change as gears are selected and when lockup occurs. (please correct me on the TC assumption)

I suspect Total ATF has sufficient differences in viscosity to possibly cause fluid noise or cavitation - what do you think?

The Total ATF is thicker (higher Viscosity) that the Penrite and Penrite is a bit thicker than Toyota WS. Toyota WS has the best viscosity index but for this issue the VI isn't relevant.

The other option that could cause this is if something got into the transmission. I checked that the old seal came out with the filter and the new one is correctly fitted.

Please see screenshots of all 3 oils.

View attachment 212108

View attachment 212109


View attachment 212110

Let me know what you think could be causing this?

We used total MV LV ATF when we switched to toal products in the hyundai dealership, we didn't have issues there.

 

[AdrianH]

We used total MV LV ATF when we switched to toal products in the hyundai dealership, we didn't have issues there.

Thanks for letting me know, happy it works for you, I see Total recommended stickers on inside of windscreens on Kia in Australia

 

[supber_2206]

I just change my Toyota's transmission oil with Castrol Transmax ATF Dex/Merc Multivehicle (which is claimed to meet Toyota WS requirement). I read ur thread and suddenly worried about my vehicle

 

[AdrianH]

I just change my Toyota's transmission oil with Castrol Transmax ATF Dex/Merc Multivehicle (which is claimed to meet Toyota WS requirement). I read ur thread and suddenly worried about my vehicle

It might be OK, best to evaluate before worrying. I had a vibration and a “whooo” sound from mine.

I am on my 3rd OCI now, in the 2nd OCI cycle I had Penrite synthetic in mine for about 4 years 50 K km and it was fine. Looking at the kinematic viscosities, the Total must have been just a tad too thick for the transmission oil pump.

After flushing 12 liters using genuine Toyota WS it’s all good!

Hope yours is fine

 

[AdrianH]

Update on this:

After flushing 12 liters using genuine Toyota WS it’s all good!

 

[supber_2206]

It might be OK, best to evaluate before worrying. I had a vibration and a “whooo” sound from mine.

I am on my 3rd OCI now, in the 2nd OCI cycle I had Penrite synthetic in mine for about 4 years 50 K km and it was fine. Looking at the kinematic viscosities, the Total must have been just a tad too thick for the transmission oil pump.

After flushing 12 liters using genuine Toyota WS it’s all good!

Hope yours is fine

As i see the kinematic viscosities, the Castrol is even thicker than Total Hope all will be fine