BG Syncro Shift II from Optimum Performance

[Optimum Performance]

WI'll I benefit more from the other rear end oil you posted about. he different weight.

Answered Below

I'm definitely going to switch as soon as budget permits. So pissed I couldn't get this week but soon. Is there benefit to the other rear end fluid? I noticed two weights

Sorry I missed this post

What are disadvantages for street driving? Just worse fuel mileage?

Answered down below

diff fluid isnt going to have any noticeable effect on mpg. The higher viscosity at high temps 140 vs 90 will maintain lubrication better when hot, such as running on the track.

Couldn't have said it better myslef

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[5starr0]

Dat color

 

[NightmareMoon]

how involved is changing out the fluid?

Its not too bad. The instructions and kits from Optimum are really great, but you still need some tools.

You'll need a jack and jackstands to get the car up in the air.

You'll also need some basic hand tools (8mm allen wrench, an 8mm socket, and a short socket extension if you're doing the transmission, and/or a 3/8" driver if you're doing the rear diff), something to drain the old fluids into, and a torque wrench is always recommended.

It only takes maybe 10-30 minutes to change the fluid one the car is up in the air.

 

[JuRuKi]

what is this rear diff fluid change? What does it do?

 

[Star711]

I switched from Royal Purple Syncromesh transmission oil to the BG Syncro Shift II transmission oil a few days ago (and also changed out the stock differential fluid with the BG fluid). My main objective was to try to reduce the transmission noise from the diff bushings I was forced to install a few months back (I couldn't buy replacement oem bushings independent of a sub frame!). Thankfully there's a noticeable reduction in noise (approx. 35-40% to my ears over the Royal Purple) and the gear shifts are smoother too (approx. 30% smoother than with the Royal Purple trans oil). I wish I had just gone with BG in the first place. Actually, I wish I had never fiddled with the stock differential bushings.

 

[NightmareMoon]

what is this rear diff fluid change? What does it do?

Nothing for most people. Well, I think there is probably a factory recommended service interval to flush the diff fluid, but its going to be pretty long.

Those of us concerned with changing diff oil are tracking our cars and are concerned about performance at high temperatures and general accelerated maintenance schedule due to extra hard use.

Its a waste of time and $$ changing the diff oil for a street car, you won't notice any difference.

 

[JuRuKi]

Good to know. thanks for the info!

 

[16s550]

I'm going to need my rear end gave a warning at track today. Plus I want to see if shifts really get smoother.

 

[Todd15Fastback]

I'm going to need my rear end gave a warning at track today. Plus I want to see if shifts really get smoother.

What type of track? Road course or drag strip? What was the warning? High temp?

 

[Optimum Performance]

I'm going to need my rear end gave a warning at track today. Plus I want to see if shifts really get smoother.

What type of track? Road course or drag strip? What was the warning? High temp?

The 75W-140 seems to help many of the 3.73 cars with the warning.

 

[Todd15Fastback]

The 75W-140 seems to help many of the 3.73 cars with the warning.

Good to know.

 

[16s550]

What type of track? Road course or drag strip? What was the warning? High temp?

Yes it was high temp warning and told me to reduce speed it was in last lap of 20min trial so I just pitted and called it a day. I'm thinking it maybe happens from having the traction control on sport mode. Maybe it's trying to hard to control spin? I was at thunderhill raceway in northern California.

 

[Todd15Fastback]

Yes it was high temp warning and told me to reduce speed it was in last lap of 20min trial so I just pitted and called it a day. I'm thinking it maybe happens from having the traction control on sport mode. Maybe it's trying to hard to control spin? I was at thunderhill raceway in northern California.

Thanks for the info. I wish the '15s had this warning but I don't believe they do, right?

 

[Optimum Performance]

3.73's spin a lot faster inside the differential for the same ground speed. 16+ with 3.73's.

Traction Control etc do not appear to cause excess heat, only in the rotors. I track day with nannies on will glaze the rears. They are pretty busy. My RR caliper boot is melted (outer) You are better off not knowing how hot its getting, its hot. ;) #15FTW

 

[Optimum Performance]

Its also why I have the third batch of fluid in it in 10k miles.

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