Overheating engine... run Thin or Thick oil?

[Quattro Pete]

Originally Posted By: Pop_Rivit
Originally Posted By: veryHeavy
My ancient 1 liter/3 cylinder car likes to overheat when climbing steep mountain grades during California summers. 5W20 is the recommended oil, but I switched to 5W40 for more high temperature protection.

Thinner or Thicker?
Which is better for a very hot engine?



Why not drive the Challenger you pretend to have or the Honda you pretend to have?

The 1-liter 3-cylinder engine is in his Honda Insight Hybrid.

 

[69GTX]

If I could afford to shop for a new 2017 Dodge Hellcat, replacing/fixing my overheating 1986 beater would have already occurred. Did you just move to California from Minnesota in the past month or so? Shouldn't be any overheating issues in a Minnesota winter.

 

[kschachn]

I still want to see a picture of the Challenger.

 

[Bgallagher]

Originally Posted By: bioburner
Originally Posted By: Kuato
Ancient and overheating tells me your cooling system isn't what it needs to be. Radiator probably has some scale buildup inside that is reducing cooling capability. If that's up to snuff...well...oil is not going to make enough of a difference in cooling so thicker would be better. I'd be concerned about your head gasket.

The old 3 hole doesn't have the guts to do any elevation my guess. Probably a carb job too.


I am thinking both should be addressed.

 

[veryHeavy]

Originally Posted By: Pop_Rivit
Why not drive the Challenger or Honda you pretend to have?

(1) The overheating engine IS a Honda... with a bad battery too. I figure I can get a few more miles out of it. (2) Drive the Challenger in the salt? No way! I save that car for the PCH. (3) Why presume I only own 1 car? Used cars don't cost that much, so I have several of them. I'll probably trade the overheating Honda for the new Cruze "whisper diesel"

(4) I used to lease a hydrogen car, but that thing was a piece of junk (only 200 mile range and took 20 minutes to refill), so I got rid of it. Hydrogen is stupid.

 

[Ohle_Manezzini]

Originally Posted By: MolaKule
Thicker oil means more heat energy going into the oil and raising overall temps.

Clean out the radiator.


Doesn't also mean better protection in an overheating event. Theheat will soon endup in the bulk oil, no?

 

[kschachn]

Originally Posted By: veryHeavy
(4) I used to lease a hydrogen car, but that thing was a piece of junk (only 200 mile range and took 20 minutes to refill), so I got rid of it. Hydrogen is stupid.


Considering there are a grand total of... zero hydrogen fueling stations in Minnesota, that would suck. Unless of course this was in some other state?

Can you post a picture of your Challenger?

 

[BrocLuno]

Originally Posted By: zeng
This is where thicker oil with higher margin of safety than thinner oils comes in .............. though underlining coolant temperature phenomenon is to be managed.

Edit:
a typical 5W40 at 120*C has similar operating viscosity protection level as a 5W20 at 100*C.
20*C is huge margin btw!
I would ignore indiscernable difference in heat transfer coefficient and churning heat loss, more so at operating temperatures.


+1

Absolutely, and right on the money

You know this may be a timing issue... Advance it a few degrees and see if it helps?

 

[HerrStig]

Among other "small things" you can do is get out the "100 knot tape" and cover all the gaps where air might leak around the radiator instead of going through it. If the "unit" has an electric cooling fan setup make sure it's working OK. If turning on the heat full blast cuts the overheating down the radiator is probably not flowing coolant correctly.

 

[bullwinkle]

Not sure what the price of an Insight radiator is, but when my XJ can (& will in the spring) get a brand new aftermarket radiator for around $55, it's cheap insurance.

 

[aquariuscsm]

What about running straight water with a bottle of Water Wetter? Just a hunch

 

[BrocLuno]

Another thing we have not mentioned is a ring soak. I use Break-Free carbon gun solvent. It's possible that compression is down... It's also possible that freeing the rings can bring it back up 10~20 PSI and that might help - a lot

 

[bunnspecial]

I'm in agreement with fixing the cooling problem first.

Pull the radiator and have it boiled or just replace it. Check(and probably replace) all the hoses along with any other pressure components in the system. Cracked plastic overflow tanks aren't exactly unheard of. A system that won't hold pressure can boil at too low of a temperature and cause problems.

The thermostat is ALWAYS suspect after an overheating event to the point where I just make it a habit to spend $5 to replace them. Granted sticking open is more likely than sticking closed, but some halfway position between the two can impede the flow of coolant. BTW, I'm not a fan of fail safe thermostats.

A neglected cooling system can have a lot of sludge and other crud in the water passages. A good flush can help things a lot. Someone else mentioned the water pump-I'd give it a good look and make sure the impeller is in good condition.

 

[Olas]

Water pump, thermostat, radiator, fan switch and fan.

 

[Boss302fan]

Originally Posted By: MolaKule
Thicker oil means more heat energy going into the oil and raising overall temps.

Clean out the radiator.


Ditto. Having someone check your cooling system should be a first on your list. I have found that some thinner oils will run slightly cooler because they flow better and I learned this with my Jaguar V12. Maybe try a 5W30 or 10W30 PYB, etc after you get your cooling syatem repaired. Is 5W20 really recommended by the manufacturer of your older engine? You are in California?

 

[fredrik94087]

As others have mentioned, you want to address your cooling system first.

I noticed my oil temps were climbing about 20F higher than normal. I started logging/viewing both coolant and oil temps.

To my surprise, coolant temp went up first and oil temp followed until the oil got to temp (205F).

Sitting in traffic, the coolant temp started to rise. It went up to 214F and stayed there. The oil temp followed and went up to 217F.

Once traffic started moving, the coolant temp went down quickly and oil temp went back down.

I wouldn't have believed it if I hadn't experienced it first hand.