Mine says 5W30!

[RedRagTop]

My oil stick cap specifies 5W30 oil. Yet I read all kinds of different threads here describing the use of 10W30 or others. I take it there is no harm in disregarding this factory requirement or what?:confused

 

[Blade]

Mobil Synthetic 5W30 in the C5 only.

Gas it with Amoco or Mobil Super.

 

[fast.asleep]

In my experience there is no harm at all.

I switched to Mobil 15-50 years ago without any ill effects.
The only side effect is my oil temp is 15 degrees cooler than when I had Mobil 5-30 in there.
(In any sort of heat 5-30 is going to have the consistency of water. I chose the oil that gave me the most protection for my engine)

Will

 

[HTRK-1]

When the engine is hot there is no difference in viscosity between 5W-30 and 10W-30....I'll stick with GM on this and run 5w-30

 

[fast.asleep]

When the engine is hot there is no difference in viscosity between 5W-30 and 10W-30....I'll stick with GM on this and run 5w-30

let me get this straight, 5-30 has the same viscosity as 15-50?
If so, how hot does an engine need to be to accomplish this?
How long does it take for the engine to become hot enough to do so?

Obviously a change in oil will not keep the engine cool indefinitely, but it will be cooler for a longer period. Doesn't lower oil temp combined with lower coolant temp result in a cooler engine??
If not please explain,

Will

 

[Edmond]

I thought that 5W-30 was meant for new or newer cars. Obviously, our C4's aren't new anymore. But I made the switch to 10W-30 synthetic and I haven't had any bad results.

Synthetic is also supposed to not break down as easily at higher temperatures than the regular oil. You can get a 5 quart container of Mobil 1 Synthetic at Wal Mart for $18 or so.

As for coolant temperature, that really depends on your coolant/water mix. Water takes an extremely large amount of energy to heat up or cool down. I think the term was "thermal inertia" or something like that. Using Water Wetter will help it out, especially during the summer season.

 

[Bonnell]

Hi Everyone,

Edmond, my '88 runs a little hotter than I prevfer with the a/c on and the outside temp at close to 100 degrees. Do you really notice a difference using water wetter? What is the mix?

Thanks,

J

 

[Vettelt193]

Edmond, oil temp will affect coolant temp, and vice versa. Everything is related in our engines:t

As far as viscosity, and which one to use.....

5W30 was put in by the factory for a couple of reasons.... the first reason is gas mileage. 5W30 has very low friction, so it gives the best gas mileage, which lowers GM's gas guzzler taxes. The second reason is the wide range of temperatures the car will be sold in. For extreme cold temperature, 5W30 is great.

For all of us in warmer climates, 10W30, 10W40, or higher, may be better for protection from heat.

 

[Tuna]

;stupid I agree ( we need a flag that says "I agree!" )

Here in the heartland, it's a lot hotter than it is colder so we don't need the cold capabilities of 5W30. Therefore, all my cars get 10W30.

 

[robert kirk]

I use 15w50 mobil 1 in the 92. No problems at all. It gets hot in texas and the 50 part of this # is what i am after. We might get 1 or 2 days a year the temp drops below freezing but not much. We get lots of days of temps over 90. with 5w30 on hot days the oil temp would run 245 and the pressure would drop to 25 or so. With 15w50 the oil temp never goes over 220, and the pressure stays at about 30 to 32. Heat load plays a big part in what oil viscosity you should use. just my 02w40 robert

 

[grapeknutz]

The only thing I can add is 15w50 takes longer to come to operating temp could and I repeat could cause faster wear when cold.