chasb4570

We have an '04 six speed coupe that just turned 14,000 on the clock. Purchased last Oct. with 11,700. Original owner kept Moble 1 in the engine. When I changed fluids in Feb., I used Castrol Edge. Always have been a Castrol fan. Not a fan of BP.
This summer in Phoenix the car ran right at 199F-207F with the oil temp running between 15-20 degrees more.
First question: Is it too early in car's life to switch to high mileage Moble 1 such as 0-40?
Second question: Thinking of replacing radiator this winter with a DeWitts just as preventative maintenance. Which would be a better choice? Internal rad oil cooler or an external cooler in front of the condenser?
Thank you for any replies and info.
Chas

Corvette_Ed

You should be using Mobil 1 to begin with as the Castrol you are using does not meet GMs minimum requirements. Switching to the 0-40 weight Mobil 1 would depend on where you live and the temps that your car is exposed to.

Why are you putting an oil cooler on it? The oil is supposed to run at around 220 degrees. Running lower than that will cause you problems in the long-term. That said, a DeWitts would be a good upgrade, but it's a little bit of overkill unless you're racing your car or running a supercharger.

leadfoot4

If you're NOT a fan of BP, as you say, and I assume you mean 'British Petroleum', then why the Castrol? Castrol IS a BP product.

If you're in Arizona, which is a warm climate, why a 'zero-something' weight oil? 5W-30 is just fine, but if you want something with a little more weight, 10-30 would also be just fine. I use 5W-30 Mobil1 High Mileage oil in my '01, because the high mileage oil formulation has a higher level of ZDPP. It's formulation is closer to the Mobil1 that GM called out for when our C-5s were new.

Smoken1

I use 5W-30 Mobil1 High Mileage oil in my 02 and I really don't consider 76k high milage

leadfoot4

My car has only 24,000 miles on it, but I use the "high mileage" formula, just for the additional ZDDP content......

c4cruiser

Oil temps typically run 10-20 degrees above coolant temps so what you see for oil temps should be "normal". Also, GM tested these cars at their Mesa, AZ proving grounds in both very high air temps as well a very cold temps and I would expect that they saw oil temps higher than what you have seen and for long periods at high speeds.

I'll agree that you should return to Mobil-1 5W-30 or even use their 10W-30. With the low miles, there would be no reason to use a high mileage oil unless you drive the car hard such as autocross events or track days. Using a 0W-40 won't give you any benefits unless you drive the car in very cold temps (which is what the "0" rating helps with).

Why a new radiator? Unless there has been some cooling problems or the coolant hasn't been changes over the life of the car, the OEM radiator will work fine even for the Phoenix summers. You may want to consider something like a 160 or 180 degree thermostat.

You could add an external oil cooler, but IMHO, I don't see it as really necessary for a street car. One thing to remember about extra coolers is that the same incoming air has to cool everything; the oil in an external oil cooler, the A/C refrigerant, and then the coolant in the radiator. As the air passes thru each components, it gets hotter and the next component has a harder time getting stuff cool.

Last C5

High Mileage Mobil 1 does contain more ZDDP, but it also contains an ingredient that causes the valve seals to swell. This is why it's "high mileage" oil because they assume by that time your seals are either leaking or getting ready to. There's nothing wrong with using the high mileage formula except that once you start with it (a couple oil changes or so) you can't go back to regular Mobil 1. I doubt if your car needs it with your mileage.

3boystoys

Another ACD thread. If it ain't broke!!! You don't think your car was engineered to run in AZ?