Anybody have tried synthetic oil in the 940. What is the experience? Noisy valves or Not?

I bought my daughter's 940 with about 135k mi on it. Drove from the seller's place right to a Insta-Lube type of shop and got an oil and filter change (conventional 5W30). Drove it 170mi to home and did an immediate change to Mobil-1 5W30 and Mann filter. The 170-mile oil was pretty clean as drained, so I figured there wasn't much sludge in the engine - things looked OK in the cam cover, too. Last I heard the car is running fine with about 240k on it...no leaks and it gets a Mobil-1 change about every 7k-10k mi.

I've changed another 7 or 8 cars over to Mobil-1 (usually 5W30) at low to high mileages with no leaks that weren't already there, and never have I seen the new synthetic "go black" shortly after a change. With mostly highway driving, I change the S90 at 16,000km (10k mi), and the 240 every two years which is about 5-6k mi. (summer pleasure driver only).

I suggest you take all the anecdotal internet wisdom (including mine!) with a big grain of salt, and check out the websites of the synthetic oil makers. Any of them that recommend an engine flush are probably also selling engine flushes. The big outfits - like Exxon-Mobil, Castrol, Pennzoil, etc. - say don't bother. And a GM bulletin of a few years ago stated GM will void your new car warranty if you use an engine flush on their cars and then have an engine lubrication problem.
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Bob: Son's XC70, daughter's 940, my 81 and 83 240's, 89 745 (V8) and S90. Also '77 MGB and some old motorcycles

When I switched over to synthetic, the oil turned nearly black after a week. The motor had 114k and was spotless under the valve cover.

So, the oil turned black, but it was spotless under the valve cover? Meaning it cleaned the engine or the new oil was a bad idea?

that was my question too.

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'90 245 291k, '93 945 299k

Muy Estimado Don Volvito,

Hope you're well. I've used Mobil 1 in 940s for about a decade. The engines run smoothly and as quietly as does any four-cylinder power plant.

Hope this helps.

Atentamente,

Spook

I used Mobil 1 in an 88 740 right from day 1. Worked just fine. Is there any truth to the view that introducing synthetic oil in a car after years of using regular dinosaur oil can cause internal crud to start floating around inside the engine. I tend to discount this view but some subscribe to it. I probably would still have the car except it was totaled by a new driver whose license still had wet ink while my car was parked at the curb

It is a valid concern but where "should" that crud end up? Your oil filter. Unless the car was very poorly maintained the only thing this is likely to do is cause the first oil change interval to be shorter.

just plain changing the oil on a badly neglect car can cause sludge and carbon deposits to rapidly clog the oil pick-up screen and starve the engine of oil...not a Volvo but happened to me.

FYI, Mobile 1 is just a brand these days. They make full synthetic to oils that are basically just like dead dinosaurs with splash of synthetic in them for color. Still a good brand of oil but not all of them are created equal.

Good, thanks. I am going to try it. Organic oil seems to create carbon deposits faster than I want to. I end up changing the oil before it is time. Perhaps the synthetic oil will help that.

I subscribe to the idea, or fact, that that you will be cleaning all the crud out of the engine, especially the oil pan and you don't want to test the oil filter bypass valve. The 700/900 FAQ just says to change the oil after a month. There have been lots of posts on the process of you care to search. I changed the filter after 500 miles then changed the oil and filter after 1000 miles. Next change was 3000. After the 3000 mile change, depending on the type of driving I do on what car, 3-6K mile intervals.

This picture of the magnetic drain plug is from a 1992 240 B230F, 200K miles. The synthetic oil is still cleaning the ring fuzz, (cylinder wall scrapings) from the depths of the oil pan, IMHO. I switched to synthetic oil when the car had 190K miles.

TOm

Thanks and also to Ira Eisenberg and spook. I think that either way I will be OK. I rebuild this engine 40,000 miles ego. Reason: I bought the car with 133,000 and the engine was so full of junk, I mean spoons full of asphalt like crud. I decided to tear down the engine and dip it. Now I see a little deposit forming on the camshaft bolts, already. I have changed the oil a couple of times in a short period and it is cleaner, but probably it will continue to build deposits over time. I think a couple of oil changes with synthetic will clean and maintain the engine in the future. What do you think?
I should have used synthetic after rebuilding would be the right answer, but I did not.

I think you will be on a good course of action.

I have used Amsoil and Mobil 1 for many years and found as a plus that the seals, engine, transmission, and differential, do not seem to leak as soon or at all. My daughter has a 740 with 280K miles on it and the pinion seal is still the original. The differential has Amsoil 75W-90 lube in it.
On another topic, even synthetic oil will not save the rear main seal in the B230F engine if it is the cheap reddish brown silicone seal (Elring is one manufacturer). Only a Vitol (black) seal will stand up there. Strange, but the Elring type seals seem to work well other places but I am going to install only Vitol seals from now on.
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Mine: 3-940s running, 1-740 and 1-940 parts cars, and 3 John Deere 630s, dtr1:3-940s, dtr2:2-740s