dev203d

We just bought an 03 CR-V with 189k on it for my girlfriend, its clean inside and out and the price was great so the high mileage didn't bother me so much. What did concern me is that the oil change tag shows the last oil used as "10W-40".

Now I know the K24 likes 5w-20, and I've always been one to stick by what the company recommends, but I know a lot of guys will throw heavier oil into an older motor to stop ticks etc. The car is running great right now, its pretty quiet for the mileage with a few ticks after it warms up.

I would love to switch back to 5w-20 and run it on what it was designed to be on, but I don't know if that's a good idea. I don't know how long it's been on 10-40 and maybe switching to a lighter oil may uncover a hidden problem that I would rather prolong? I was just wondering what you guys think, what possible dangers there are in switching back etc. This kind of reminds me of when an old automatic tranny hasn't been flushed and people say "leave it be or you can cause more problems" type of deal. Any advice with this would be greatly appreciated as I am in a dilemma right now.

hondamark35

"heavy" oil will only hide a problem (if you have one) not truly fix or provide extra protection.

it can instead cause problems. Viscosity isn't "thickness" per se, but the resistance to flow. if the viscosity is higher than recommended, it's flow can be reduced in the smaller passage ways. in extreme cases this can starve certain areas of the engine.

higher viscosity also increases pressure in the system. this puts more load on the pump and rotating assembly which requires more power from the engine which hurts gas mileage and power output of the engine to the wheels.

so all of that to say, change the oil to the weight recommended on the fill cap or in the owners manual. any noises that arise as a result can then be dealt with accordingly. Some have even moved to 0w30 and 0w20 for better fuel economy.

I wouldn't expect any trouble though. these engines don't have much trouble even when abused/neglected. Most quick-lube places just put the same weight in everything because it's cheaper to keep one tank with 2000 gallons of a single weight of oil around back than it is to have five or six small tanks with the "right" weight for the vehicles coming through.

holmesnmanny

Use whatever oil the engine is supposed to use. It's likely they simply put the wrong oil in.

ludecz

Some people prefer using a little "heavier" oil in areas with higher temperatures and on engines with over 150k.
I don't see nothing wrong with that, but 10w40 is a little extreme. I would go for 5w30.

hondamark35

just click here and read the whole thing. it should be required reading for every automotive forum user/contributor.

holmesnmanny

They make "high mileage" oil for engines with higher mileage. You still use the same viscosity oil.

Engineers spend millions of dollars determining the best oil for each engine. It's best to trust their judgement.