Advice please.
Haven't been out of touch for quite a while, so this is an accumulation of a year's worth of inquiry. My car is garaged in South FL, and as anyone there knows, 99 degree temperatures in July and August are common. Last year I slugged through summer traffic with the air conditioner off, (and the roof off) due to certain engine overheating, in spite of a 160 deg stat.

Question 1: To where should I re-set the radiator fans to come alive, to battle overheating in traffic, with the air conditioner running?

Have been using Amsoil's lubricants, for no particular reason, other than that they are acclaimed to be superior products. But, I'm tired of paying a pile of money at retail, and forget about the bush-league pyramid scheme rip-off, involved with a factory order. (Like buying Amway soap products) I wonder if I'm kidding myself by sticking with Amsoil, for it's lauded superior quality. I've come to consider that there must be other products, like Mobil 1, RP, Castrol, Red Line, (and many more) which are more price-worthy. I suspect that the quality of other popular brands is about equal, as long as the GM Standard is met.

Question 2: Considering S FL summer temperatures, what is the consensus on switching from 5-30 weight, to a 10-30, or even 10-40 weight, given a quality product?

Lately the drive train whines slightly, but noticeably, under power, but not when I let up on the gas.

Question 3: Are there any Diff Lube recommendations, that offer proven performance, above and beyond the call of duty, and what is a good lube for the smoothest shifting possible with the manual 6 speed gear box, topped off with a MGW stick. Thanks GRT

 

I would leave the stock t-stat , flush the coolant system, clean under the radiator, use the stock weight 5w-30 .I just did my clutch and and rear diff with amsoil , very smooth shifting . These cars are designed to run hot.

 

1.regarding the overheating...
check to ensure the radiator is free from debris.... check it from underneath. often a lot of grass clippings, plastic bags, etc get stch between the condensor and radiator dropping its efficiency.

2. Any oil that meets GM4718M is good for your Vette.
I see no reason to buy boutique oils.
There is a long list of GM4718M oils
Formula Shell Fully synthetic
Quaker State HorsePower
Pennzoil Platinum
Pennzoil Ultra
Valvoline Fully Synthetic
Castrol Syntec
Castrol Edge
Mobil 1

You can get Quaker State Horsepower for as little at $18/5 qt jug at Walmart. That is $3.60/qt

5W30 versus 10W 30 both are acceptable....
5W30 gives the same high temperature protection (the 30)
But flows faster on cold starts (the 5) so it gets oil to the critical wear boundaries quicker on start up....
Stick with the 5W30

3. the rear diff again go with a Brand you trust 75W90 synthetic gear oil with 4 oz of GM (or after market) posi-traction additive. Put the additive in first so you know it is there.

4. For the 6 speed manual transmission any Dexron III ( yes that is an automatic transmission oil) is good.... With a short throw shifter you have to work harder to shift( it is physics... leverage) you can do the Viper mod and reduce the pressure on the shifter detent by removing the detent screw and putting a washer behind it.

 

Why do people think these cars run too hot? Don't you think GM tested these cars in the HEAT? Get's 90+ here in the summer too, no problems with mine with STOCK T-stat.

 

Hi dougbfresh
Thanks for your reply regarding car overheating in hot temperatures. I was referring to the temp needle red-lining to the far right, and that's a recipe for a waiting disaster. After the air is turned off, the temp returns to it's usual/normal setting. Ie: the load of the air cond is the culprit. Have a nice summer. GRT

 

When you had the thermostat replaced was the proper GM coolant bleed process performed?

If the car has a stock tune, it will go into reduced power mode before damaging the engine during true overheat.

Does the driver information display agree with the analog gauge?

Have you checked to see if any codes are set?

 

i saw this post even though its from over a month ago. my 02 corvette does the exact same, idling/traffic car overheats when a/c is on. 215 degrees when ac is off. just started now because it's finally warming up here in NC. goin to flush the radiator and change hoses to see if it fixes the problem.

 

Don't neglect to clean the radiator itself. Flush it from the back. The radiator getting plugged up dirt, leaves, miatas, and such is a common problem in the C5. B\G