Before replacing all of the fluids on my 99 FRC I did a search and found some excellent information as well as opinions on the best fluids.

Back on the road now. Here are some notes and observations:

Oil change: Can't use a vacuum pump; hose won't go past the dip stick guide. A few degrees forward rake improves draining. Used Mobile One 5W30 and Fram Extra Guard filter (like that grip material).

Coolant change: Forward rake aids draining here too. The plug is nylon with a single metal radial pin that runs in a spiral track. Use 3/16 internal hex wrench. One quarter turn CCW places the pin at 3 oclock in a removal slot (pull gently). Another eighth turn is full open but cannot be removed. I removed pin and cleaned, greased O ring with silicon grease.

With the pressure cap off 8 1/2 quarts will drain from rad, expansion tank and some from engine. Poured 8 1/2 quarts Prestone DexCool pre-mix in at exp tank and brought it right up to full cold. Ran engine to operating temp and did not need to add any more.

Manual trans fluid: Leveled car, then drained 3 1/2 quarts. Raised front for an aft rake and drained another 1/4 quart. Aprox 1/4 qt of 4.1 total is inaccessable in trans cooler.

Lot's of discussion about the best fluid here....I was concerned about the paper ring blocker filters and thier reaction to synthetics so I went with GM's latest ATF: Dexron VI. This is recommended to replace all Dexron III applications.

Leveled car. Screwed a nylon fill hose with shutoff onto each quart and placed it on top of exhaust pipe above fill port. Fed hose in, made pin hole in bottle and it gravity flowed. Applied Permatex High Temp Thread Sealant to plugs.

Differential: Had the common driver's side leak. Couldn't tell where it was coming from so I cleaned entire diff, around vent and axle seal. After it was drained and clean with drain plug (thread sealed) installed, I ops checked the vent.

My brake vac tool has a fitting that fits exactly into the fill port. I put this in with a length of nylon hose attached. Blew into the nylon hose while feeling above the vent with other hand. Could feel and hear the vent releasing, and yes it creates a slight vacuum in the diff. The vac fitting was held in the fill port by outside pressure.

Many opinions here as well about the best fluid and correct amount as it regards the well documented left side seepage. I went with Royal Purple 75/90 because it has LSD additive and it's about $10 per quart versus $28 per quart for the GM plus $4 for the additive. The Royal Purple users also gave the best reviews. Now for the amount.....

1.69 quarts plus 4 oz additive equals 58.08 ounces. I used a nylon hose on a graduated 8 oz squeeze bottle and put in exactly 58 ounces cold. This put the level about 1/4 inch below the fill port, corresponding to the belief that it should reach the fill level only when hot.

Brake fluid: Extracted old fluid and bled brakes using my vac tool.
I have used Valvoline Synpower full synthetic for years with excellent results.

Clutch fluid: Cannot of course, bleed the clutch due to the inaccessability of the bleeder screw. So I extracted the reservior fluid using my vac tool. I tried the technique of putting the nozzle fitting into the hole at the bottom of the reservior and drawing from the line, but I believe this is ineffective as there is nowhere for the replacement fluid to come from.

Instead I put about 2 onces of new fluid (Valvoline Synpower) into the reservior and observed how this clean fluid would pull dirt and old fluid up the line into the reservior like a little black inverted tornado. When the process slowed I vacuumed out the old stuff and put in more fresh fluid and it would start over. Did this about 10 times allowing the process to work overnight on the last two and fluid is now perfectly clean.

Power steering: Vacuumed the reservior. Put in GM spec. This is one of those DFWI items.

Road Test: With GM Dexron VI in the trans the shifter is much smoother and quieter with less muscle required and no problem going into any gear.

With Royal Purple in the diff the rear no longer squirms under hard acceleration and is quiet in turns. So far, no more seepage.

With Valvoline Synpower the brakes and clutch are firm and smooth. No trapped air using the clutch process described above.

Last replaced the DexCool about 3 years ago. It was reading about 0.3 volts before the drain and came out looking as good as the new stuff. After refilling the voltage was down to 0.010v.

The info from the forum was invaluable in making it all go smoothly.

 

Thats very good Information, thanks for sharing

 

So why exactly did you choose to not put synthetic in the manual trans? I just ordered 4 quarts of RP Synchromax for mine because I've heard nothing but good things about it..

 

How do you check the conductivity of the coolant? Can you use a common digital volt meter between the coolant and ground?

 

 

Put the red lead of the voltmeter into the coolant in the expansion tank. Put the black lead against ground. The metal water pump works very well for ground. Read the voltage on one of the lower DC scales.

After long service coolant begins to function like a battery. Ideally you want to read less than one volt. A few tenths is best. Voltages between 2 and 3 volts indicates the coolant needs to be replaced regardless of the 5 year/ 150,000 mile claims.

This kind of reading indicates EMD (electro mechanical degradation) is damaging internals, particularly the hoses. Look for hose damage at the ends where the hose contacts metal. Inspect for cracks (use a mirror as needed) and feel for brittleness. Use a new hose for comparison. If the hose is cracked or brittle it's EMDed.

The best thing to do is just drain and replace the DexCool every 2 or 3 years. If you do this you won't need to flush the system. 8 1/2 quarts is enough to keep the voltage down and avoid EMD. It's easy and inexpensive. You could buy 30 gallons of DexCool for the cost of a tow and repair away from home. The hoses will last almost indefinitely. (15 years +).

 

It depends on the model year. My 99 FRC falls near the end of the use of paper ring blocker filters. Some synthetic trans fluids will absorb moisture which will degrade the paper filters. Try doing a search.

Mobil One is supposed to be non-absorbant but I didn't feel it was worth the risk. Some owners have also reported problems getting into 1st or reverse after a switch to synthetic.
That plus the introdution of GM Dexron VI to replace III made it more appealing.

 

This is my weekend project. I will be using Royal Purple Max-Gear for the rear, Synchromax for the 6sp, and Dexcool with a touch of Water Wetter.

 

Good to see you were able to handle all your fluid changes with no problems.
FWIW, my 99 FRC has had Red Line D4 ATF in the trans for several years now and I have really enjoyed the smoother shifting.