Hello,
So according to my manual the oil is 5w-30 that is recommended, some say OW-20 but I stick to the cap.
Im also normally using K&N ps-1002 filter and FRAM/WIX air filter. I have 130k miles and really bad mileage, around 19-23mpg. Any recommendations.

I know Toyota ATF WS is recommended but could someone explain if a different fluid is needed for rear transmission? Do recommend good alternatives to Toyota brand as well. And how much fluid will I require for both axles.

Lastly, what type of steering fluid is needed, the manual says transmission fluid but not for electronic steering, which the rx400h has, so whats our model specific requirement? And how much fluid is needed?

P.S. Has anyone messed with the inverter fluid? Do we need to replace it?

 

First I would dump the K&N filter. The oil in it will contaminate the MAF sensor, which could effect your mileage. If you are in Michigan I would run 0-20 weight. I run it in Sacramento and we get 105 degree temps. I have 246k miles. Remember in winter your mileage drops as the ICE engine (gas engine) is on more because of heat. I always use Toyota or Wix oil filters. The ATF required for both front and rear is WS. Especially front as it is a CVT transmission tied with the hybrid drives. I also only use Toyota Red or Pink in the radiator system for both the ICE and Hybrid systems. The steering is electric, no maintenance required. I must say I have not changed the hybrid coolant. But I have had the cooling pump go bad, so yes it has been topped up. By the way the MAF can be cleaned with MAF sensor cleaner available at any auto parts store. DO NOT use carb cleaner. at your mileage have the spark plugs been changed. They are due at 125k. The timing belt should have been done at 100k miles. Top of the morning to you.

 

Thank you. How much transmission oil is needed? For both axles?
Is there any reason for a strong steering vibration on certain surfaces? The bearings should make some noise and there is none of that. So if there is no fluid, and no bearing issue, what else could be the problem?

 

The forward transmission takes 4.1 quarts the rear takes 2 quarts. Vibration could be lots of items, bad tie rod ends, control arms, upper strut mounts, even bad tires.