Diff fluid makes car feel slower

[armykyle1 [HACKED ACCOUNT]

So I got the optimum performance fluid kit for the transmission and diff. But I went to the heavier diff fluid 75-140, in hope to calm down some the noise from the diff. While the transmission is a bit smoother and the differential is making less noise now. The car feels slower. Maybe I'm over thinking it or imagining. But it really does feel slower. I'm hitting the track Wednesday and I want to squeeze everything out of it.

Should I switch it back to 75-90 with something I can source locally until i can get another order of the BG fluid? Or am I imagining shit?

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[moffetts]

Youre imagining things.

 

[EXP Jawa]

I've been in the diff business for 20 years and haven't come across that one - where that change in lube created perceivable difference in drag. The difference in viscosity between 75W90 and 140 is marginal enough to be lost in the shuffle amid everything else that's going on in the car. Are you sure the brake isn't dragging or something? Otherwise, I suspect placebo effect...

 

[jasonstang]

It's just summer time and you have the AC on.

 

[armykyle1 [HACKED ACCOUNT]

I've been in the diff business for 20 years and haven't come across that one - where that change in lube created perceivable difference in drag. The difference in viscosity between 75W90 and 140 is marginal enough to be lost in the shuffle amid everything else that's going on in the car. Are you sure the brake isn't dragging or something? Otherwise, I suspect placebo effect...

I don't think so, but I can double check them later today.

It's just summer time and you have the AC on.

The AC get turned on in February lol.


One thing I have noticed since I've had the car is that sometimes it does feel faster than other times. I always drive the car in track mode, unless it's raining.

 

[BmacIL]

I don't think so, but I can double check them later today.



The AC get turned on in February lol.


One thing I have noticed since I've had the car is that sometimes it does feel faster than other times. I always drive the car in track mode, unless it's raining.

Humidity, fuel make a pretty big difference in perceived power outside of temperature. The dry, cool mornings here in the spring are AWESOME.

 

[wireeater]

I don't think so, but I can double check them later today.



The AC get turned on in February lol.


One thing I have noticed since I've had the car is that sometimes it does feel faster than other times. I always drive the car in track mode, unless it's raining.

What kind of fuel do you run? Bad gas quality could pull timing which you would feel.

 

[jasonstang]

Humidity, fuel make a pretty big difference in perceived power outside of temperature. The dry, cool mornings here in the spring are AWESOME.

People don't believe me when I tell them I can feel power difference when the temperature and humidity changes.

 

[wireeater]

People don't believe me when I tell them I can feel power difference when the temperature and humidity changes.

Clearly those people don't understand how cars make power.:lol:

 

[armykyle1 [HACKED ACCOUNT]

Humidity, fuel make a pretty big difference in perceived power outside of temperature. The dry, cool mornings here in the spring are AWESOME.

The humidity has picked up and the temps are a little higher. Not a crazy difference though.

What kind of fuel do you run? Bad gas quality could pull timing which you would feel.

Same tank before and after the fluid chance. I always 93 from busy gas stations and I run a little octane booster too.

 

[Mike's Mustang]

You're used to hearing certain noises at certain speeds. Now you're not hearing them so it seems slower.

 

[armykyle1 [HACKED ACCOUNT]

You're used to hearing certain noises at certain speeds. Now you're not hearing them so it seems slower.

So you're saying I need to make my exhaust louder?

 

[Optimum Performance]

You'll be fine. Take out your rear seat then the car will make all sorts of new noises and it will feel faster again

 

[Mike's Mustang]

So you're saying I need to make my exhaust louder?

If it's stock, most definitely.

 

[wildcatgoal]

I have 75w140 from OP and my car is not slower.

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