dot3 is more hygroscopic so should be replaced more often than dot4.

if it can use 3 or 4, it's OK for either. but if system says dot4 only then
don't use dot3 in a dot4 system






EDIT: I got it wrong. dot3 is less hygroscopic but has a lower boiling point
dot4 is more hygroscopic but has a higher boiling point

 

dot3 is more hygroscopic so should be replaced more often than dot4.

Isn't Dot 4 more hygroscopic than Dot 3?

 

Page 675 in the Owners Manual, you can use either DOT 3 or DOT 4. On the brake fluid reservoir, it should be printed with what it needs.

 

For topping off, If there is a way to know what Toyota used from the factory, (Dot 3 or Dot 4) personally I would stick to that. Even though they are compatible, I am of the mindset not to mix chemicals unless I have to. Just what I would do.

If it is impossible to know which Toyota used from the factory, I would use Dot 3 in humid climates and Dot 4 if I rode the brakes down mountain passes a lot or towed. Also under these severe conditions (towing or riding brakes down mountains), I would do a brake fluid flush and change to Dot 4 on Toyota's severe service Maintenace schedule.

 

An advantage for using DOT4 is that it has a higher boiling point than DOT3, useful especially when braking a lot under severe conditions such as mountain downgrades.

 

I have the 2019 Rav4H. As per the owners manual, the recommended fluid is either FMVSS No. 116 DOT 3 or SAE J1703 brake fluid OR FMVSS No. 116 DOT 4 or SAE J1704.
What is everyone using (DOT3 vs. DOT4)? Are there any benefits of one over the other?

Resurrecting this as I could not find quantity in search. I am helping friend do nearly 100K services, & I one would be brake system flush. She had oil changed out of town & they said 5mm left on pads, but just the typical checklist for rest. I have not done a flush for several years, but used to just grab Prestone DOT3, 32oz bottle & that would cover it easily. With Gen5 specs shown above, either DOT3 or DOT 4 is acceptable. Since it is a flush, could be either at this point, but in checking availability at local AutoZone, I see besides the former generic bottle, they now have a "MAX".
Has anyone used the MAX, can't imagine it could be worse, and is only $3 more for the DOT 4 over DOT 3. It cover both SAE specs, and should be 95% of total mix after flush.
She commutes a couple hours & goes back and forth 6Kft elevation change each way, so I am leaning towards DOT 4.
So for Gen5 is 32oz still enough?... and would you go for the MAX version??
Thx

 

I would just stick with the DOT4 and 32OZ should be enough. This is totally fine for regular driving. If you brake fluid is boiling then there is a problem.

 

32 oz by AI search