Pentosin super dot 4 brake fluid for g37x q40
 

I'm doing a stock to akebono brake upgrade and grabbed the pentosin super dot 4 for brake fluid. It seems to be the highest quality/performance fluid available on the shelf at AutoZone.
It was that or the standard prestone dot 3.
It's for a 2015 q40 awd
Manual specs Nissan heavy duty dot 3 or equivalent
Which is quite an open statement.

I have made the best choice?

https://m.autozone.com/brake-and-power-steering-fluid-additives/brake-fluid/pentosin-1-lt-super-dot-4-brake-fluid/579851_0_0?location=

There will be differing opinions, but your choice will exceed OEM fluid performance, so yes, you made a good choice IMO.

Thank you sir
i shall proceed then
:)

I used this in my brakes few years ago. After a thorough bleeding/flush, I found the pedal mushier than usual. I never had any leaks and use a powerbleeder to push new fluid through. It bothered me enough that I changed to something else. Using prestone dot 4 now in both reservoirs.

My understanding is it's best to just stick to whatever brake fluid is recommended. Per Stoptech......."DOT 4 fluids are also glycol ether based, but have a measure of borate esters added for improved properties including increased dry and wet boiling points. A seldom talked about characteristic is that because of this chemistry, the DOT 4 fluid will have a more stable and higher boiling point during the early portion of its life, but ironically once the fluid does actually begin to absorb water its boiling point will typically fall off more rapidly than a typical DOT 3. By FMVSS116 standards, DOT 4 fluids must have a minimum dry boiling point of 446°F and a minimum wet boiling point of 311°F.

DOT 4 is the grade applicable to most race engineered brake fluid in the world today, especially with regard to viscosity limit. Note that although the DOT 4 designation has a minimum dry and wet boiling point, a DOT 4 racing brake fluid may have a dry boiling point over 600F. Its viscosity is challenged, however, to be under the viscosity limit of 1,800 mm2/sec. Some claimed racing brake fluids exceed this important limit. Caution should be exercised if these fluids are used in race cars with ABS systems. This does not mean that DOT 4 fluids are necessarily better than DOT 3 fluids. Remember, the boiling points listed are minimums. There are certain DOT 3 fluids with higher boiling points than some DOT 4 fluids. The real differentiating factor is that DOT 4 fluid should be changed more often than a DOT 3 fluid, because of the effects and rates of water absorption."

"One last note on the DOT ratings: Systems designed for a particular type of fluid (especially prior to the wide distribution and use of DOT 4 fluids) should continue to be filled with that fluid. For example, in a car that was delivered with DOT 3 fluid, the internal components of the system (seals, brake hoses, and fittings for example) were specifically designed and tested for compatibility with the chemical composition of DOT 3 fluid. Because the DOT 4 grade fluid typically contains a different chemical composition, compatibility of system components may be an issue."

Nominating you for post of the day

@mummy2, Thanks for the explanation. My issue with the pentosin fluid was evident during the first drive after installation. My guess is it has other characteristics that don't work well with the G's hydraulics. It's been 2 years with the prestone fluid. I'll either flush it in the next month or next spring, depending on motivation :).

My previous fill was Pentosin super dot 4, which was in there for about 30-40k. No problems. Current fill is ATE type 200 because i found a sealed can in my garage. It all works just fine. Damned if i can tell the difference between any of them. I can't really comment on differences in pedal feel as the 2+yo fluid was replaced along with brakes and rotors, so obviously things will feel less mushy

note that pentosin makes an LV (low viscosity) dot4 that will work but is not needed in our vehicles

The LV fluid is better suited for cold climates (alaska?) I suppose it's possible some air got in when I did the flush. I've been using the power bleeder for a number of years now with this car without any such issues so who knows. Agreed, one data sample is not enough to draw a conclusion.

the LV fluid is for cars that require it. I know some Meecedes do and I'm sure other makes do as well. I dont think it has anything to do with operating temperatures. It will work in systems that do not require it but im not sure what effects it would have regarding subjective things like pedal feel.

Did you change any other components when you did the flush? Correct order? Abs disconnected?

Look at the data sheets on this page - Pentosin . They address cold temps there.

Brakes are fully stock. Correct order. No, abs not disconnected. Never disconnected abs before (or after).

disconnecting the ABS module (near the brake master cylinder) or the negative battery terminal; is a requirement in the service manual during a brake fluid flush. That might be the cause of your mushy pedal. maybe some old fluid or bubbles that weren't evacuated from the abs system?

I had to look that up in the FSM, but you are correct, they do advise disconnecting either as stated above. What's unusual is I've never disconnected anything with any other brake fluid and the pedal was just fine. Same bleed method using the motive power bleeder. Never had issues of air in the system as all bleeds were always maintenance related, not repair. Maybe a bad batch of fluid - it did come from pepboys. Who knows how long its been sitting on the shelf for. I doubt most shoppers at the store buy the most expensive brake fluid for their uses.

When I did my flush after my caliper change i left the car running. Saw a tip online to leave the car running, having something to do with the abs system. I used the one man bleeder kit from Walmart, https://www.walmart.com/ip/Hyper-Tou...-Kit/173745566, and when I would go and check on the fluid level i could see the bubbles coming up through the master cylinder. I've never had a pedal this firm in all my years of owning a G.

I read that LV brake fluids are fine for all cars but at higher temps it does effect their viscosity. So it isn't to be used for the track. So they say just use it if your car calls for it. You won't see any benefit if your car doesn't call for it.