Looking for input before changing transmission fluid in manual transmission and rear end. What is the best type of fluids to use. I have read several inputs saying to use royal purple and some not to. Please let me know the best to use. Pre-thanks for the information.

 

Do a search.

Youll get all sorts of replies varying from royal purple, amsoil, dex III, etc etc.

Personally ive got RP in my Trans right now and wont use it again. And I just changed the RP in the diff to pennzoil 75w90 syn w/additive.

 

Just looked at your profile,,and you have a 1999,,soooo you do have to watch what you put in!! DO NOT use Mobile 1 synthetic and it will ruin the syncro blocker ring facing.The only synthetic that I know to be safe for sure IS Royal Purple syncro max. Any brand Dex III is stock replacement. I used R.P. and was satisfied,,but I had over 55K,, and I think ANY new fresh fluid would have improved things as the stuff that came out was REALLY crappy looking and smelling!!! Just open the top plug (fill plug) first then drain plug and drain. make sure you have a way to pump the new fluid in. Easy DIY project,,nice results!!!

 

How many miles?

 

Alongside 'which exhaust' and 'column lock', 'which oil/fluid' must rate as one of the most popular posts on here. After reading many posts on this subject I decided to go for RP in engine, trans (6 spd) and diff. Up to now I've not been able to give the car a decent test due to the crap weather but I'd be intersted to learn about the reasons for changing back from RP to something else.
I'm a great believer in collecting as much info as possible before doing anything to the Vette, you've done the best thing by posting on CF, this place is great.

 

I bought my 99 c-5 in January 2010. I bought it off E-Bay with 73000 miles on it. I am the third owner, and the vehicle was very well taken care of. I want to change all the fluids so I know when they were done. Every little question that I have had was answered on the forum with excellent results. I bought a new battery the day I gpt the car, so when my computer gave me all the weird faults, and I was told the battery was bad, I figured that answer was going to be wrong, but just like every other answer, the forum was right. The battery went out in 90 days. I have read the pros and cons about royal purple so I don't want to screw something up. The owners manual says to add 4 oz of sync oil and then the differential fuild, and just use Dec III oil. Trying to gather all the facts before changing. Thank everyone for all the help.

 

Add enough lubricant to raise the level to the bottom of the filler plug hole.

To add lubricant when the level is low, use SAE 75W-90 Synthetic Gear Lubricant (GM Part No. 12378261) or equivalent meeting GM Specification 9986115. To completely refill after draining, add 4 ounces (118 ml) of Limited-Slip Differential Lubricant Additive (GM Part No. 1052358) or equivalent. Then fill to the bottom of the filler plug hole with the Synthetic Gear Lubricant.

Basically the procedure is lift and support vehicle, clean dirt from plug, remove plug and washer. Drain fluid.

Important note: Do not operate the vehicle at wide open throttle for a minimum of 480 km (300 miles) after refilling the differential with lubricant and friction modifier. Scoring of the ring and pinon gears may result, leading to differential noise.

Tighten drain plug to 35 Nm (26 lb ft).

 

You can never go wrong with what the factory recommends

 

the fluids are easy to change.... the arguments begin when you talk about different brands of fluid.....

this past week i changed 1 o2 sensor,
changed the oil and filter
changed the trans fluid (manual)
and changed the diff fluid...

easy

 

Tommie is right,all fluids are ez to chng.

(In my 02Z)I use Penn Plat 5-30 oil,Wix #51042 filter and RP trans & diff fluid.Any good name-brand full syn fluids should be fine.

Be sure & change the brake & clutch(if manual) fluids often.

\db2
Carolina

 

NOT for the transmission!!!97 through 2000 the tranny has fiber(often refered to as paper) face blocker rings. Some(like Mobile 1) synthetics will erode the facing and in short order have you looking for a transmission rebuild. 1 on had carbon fiber facing and will work with ANY synthetics. His is a 99 and Royal purple and I think Amsoil are safe,,others may not be
And for the record differential fluids need to check the bottles,, ones like R.P. have the limited slip additive in it . Some do,,some don't!!

 

You might want to get some magnetic drain plugs before changing all of those fluids

 

Lots of opinions on type of fluid but my buddy has a 1999 and at about 180K he has had no problems with regular changes performed at the dealer with the all GM brand fluid. His car is a daily driver and does not see any track duty :-)

For me (5-6 track events a year)

Mobil 1 in Motor (every 3K)
Castrol LMA In clutch (every 1500)
ATE in Brake Lines (Before each track event)
Amsoil in trans and Diff (One time a year)

 

I have a 99 as well and I have Amsoil Torque Drive (ATD) in the tranny and Sever Gear 75w90 in the diff (no additive) and everything is very nice. Had RP before but even with only 12,000miles on the tranny the Amsoil seems much smoother. I'm now running their 0w30 Signature Series oil and will see what the oil analysis says in a few thousand miles,so far it seem to have quieted the motor down a touch.

 

1999 c-5 hardtop with 6-speed trans.
I use royal purple oil, transmission and rear diffrential runs great, would not consider using anything but royal purple.
Dont forget to add 4oz limited slip additive in rear diff. Good luck. ALSO USE ROYAL PURPLE IN MY MAZDA MX-5, HONDA RIDGELINE, TOYOTA TACOMA PU, AND VTX 1300 MOTORCYCLE. THERE IS NOTHING BETER. GET IT?

 

Link...
http://64.209.142.240/faq/tutorials/tranny.htm

 

Well, I don't agree with ya that RP is the best stuff out there. I had it in the tranny, but it didnt seem to feel all that different than the previous used factory fill. After 12,000miles I swapped it to Amsoil ATD and noticed a big difference for the better. Smoother, quieter, easier shifting. Not trying to start a war, but my experience & research has led me to believe that RP is NOT the best stuff out there, (although it may be just fine).

But to the OP, do a search and you will find dozens if not hundreds of topics concerning changing your fluids, they all tend to regress to arguing over which is better though. Some will swear by Amsoil, others RP, others the factory stuff, still others something else. Some have used a brand, had a bad experience, then tried something else and liked it. Some have tried a brand and think it is God's gift to lubrication. Use what you think is best or most affordable for your car, 90% of this stuff won't hurt your car.

 

I changed all fluids over when i bought my '99 in 2005. Went to advanced Auto and bought Suction Guns to put fluids back in. It's easy. I used AMSoil ATF Synthetic in the 6 Speed transmission because it's recommended that one use that because of celulose (paper) blockers used in Corvette 6 speed transmissions in '99. Not sure your's is manual. So certain synthetic fluids may hurt the transmission. Later transmissions supposedly used composite blockers which aren't affected by other syn fluids. Don't know how true all that is, but I've been running AMSoil Synthetic ATF in the transmission for over three years now and it shifts beautifully no issues. I also added the the GM syncro fluid when I changed the differential fluid. No issues. I had a shop flush both the power steering fluid and coolant. Buy a set of Speedbleeders for your disc brakes and flush the brake fluid. One man operation with SpeedBleeders, easy to do. If you have a stick shift, get a turkey baster and remove the clutch fluid from the master cylinder and refill with synthetic brake fluid. repeat this several times until the fluid remains somewhat clear. Bottom line you're smart establishing a baseline for your fluids. After that just follow GM's recommended intervals. The car tells you when to change oil. These cars are a lot tougher than they are treated by most. Very reliable. Good maintenance yields good results. Have fun, Good luck and welcome.

 

When I switched to RP I heard great things, I noticed no difference in the trans and for the price of it ill go with something else. If I can find some I will probly go with the Amsoil, I have to do the trans this spring.

 

Thank everyone for all the information, and for everyone being sooo friendly. It is great to receive all the amazing advise.

Thanks again...