In general....is there a problem with switching motor oils on these 240s once they've accumulated thousands of miles?? Just wondering.
Cabbie2169

Or rather, none of the above.

The major reason the US manufacturers got away from 10W-40 is because the inexpensive Viscosity Index Improver additives would shear back, leaving deposits on the rings. Not a problem in a high quality synthetic 10W-40.

In general, the xW-30 will give you all the protection you need.

Nothing will happen. However, like you see in the other posts, I would not use a 10w-40. Use a 10w-30 or even straight 30w if the climate is not too extreme.The problem with 10w-40 is the additive package WILL cause more deposits in your engine.

good luck

my 240 has 400,000 kms on it, a few years ago in the summer the oil light would flicker at idle and the oil pressure gagae on my dash would read really low. I started using 20W-50 during the summer after that and the pressure is better. In the the winter i use 10w40. The reason manufactures use the lightest weight oils is that they improve fuel efficiency as they are easier for the the engine to pump and rotate.

In this Volvo I use 10-40 Castrol from day 1, that was 275000 ago.

When I was younger and had other cars, I used to always drop to 10-30 in the Winter then back to 10-40 in the warmer weather. I got over 200000 on those American engines doing it. I think 3000 mile oil changes are more important then the type or Grade you use.
Ifd you are in some seriously cold areas, you may want to drop to teh 5-30.
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'75 Jeep CJ5 345Hp ChevyPwrd, two motorcycles, '85 Pickup: The '89 Volvo is the newest vehicle I own. it wasn't Volvos safety , it was Longevity that sold me

Should be no problem at all as long as you're not doing this in extreme cold weather - in which case stick with the 5W30 until things warm up.

And if I recall correctly (no guarantee, there) Volvo recommend 15W40 for warmer temps but not 10W40. Many years ago (early 80's) GM issued a service bulletin advising that they were having problems with customers' engines using the 10W40 oils of the time. They saw unusual frequency of piston ring sticking and resulting warranty claims, which their engineers felt was due to the large amount of additives used to get that wide 10-40 viscosity spread (actually called 'viscosity index'). They told their dealers and service people to discourage customers from using 10W40. Maybe that grade has gotten better, but I stay away from it.

My approach is to use the lowest viscosity (thinnest) oil that will still handle the hottest temps I expect to see before the next oil change. For me that's Mobil-1 5W30 for colder weather, then 10W30 (or 0W40 when I can find it) for summer.

So how can I justify 0W40 when I say 10W40 is too big a spread? Synthetic oils are a very different ballgame, and obtaining that spread does not require the same chemical wizardry as conventional petroleum oils do.

You can learn a lot about engine oils and the standards they meet by going to the American Petroleum Institute site and mousing around until you find the 'lubricants' pages.
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Bob (son's 81-244GL B21F, dtr's 83-244DL B23F, 'my' 94-944 B230FD; plus grocery-getter Dodge minivan, hobbycar 77 MGB, and numerous old motorcycles)

You'd know about it by now if there was a problem... In my opinion you can get away with just about any oil in a 240.

Change frequency is a more important determinant of extreme longevity.

Use whatever makes you feel good - I feel good when oil companies get as little of my attention and money as possible. The motors don't care near as much as the owners.

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Stef -- 1981 245 B21A SU M46 chrome roofrack 320000km my volvo pages

I concur. I get my Volvos at about the same mileage (100K) and just change the oil to 10W-40, too (and I live in NJ, too). But I use AmsOil synthetic, and it really cleans out the engine over time. It's great stuff. And I feel that synthetic protects much better -- better initial flow and pressure when cold (it doesn't contain waxes that gel in very cold temperatures), and great film strength to protect even at the highest temperatures.

But if you're just putting in regular 'dino' oil, you shouldn't even notice any change going from 5W-30 to 10W-40 -- certainly, the slight increase shouldn't hurt your older engine.

Don't hesitate -- if you want to use 10W-40, go right ahead.

I have owned a number of Volvos over the years. Never been original owner. Average mileage when I got them is about 100,000 miles. In all cases I have always and continue to use 10-40 weight oil. No problems at all. I am in NJ which is mixed climate. Per Volvo I believe they say to use 10-30 weight oil. Do not know why. Curious as to what others here think.