1996 850 B5202S engine oil/spark plugs

[Teddy1975]

I have recently bought this car and I've been looking at the service book. It has been serviced fairly regularly, up until about 150k miles. After that it's more sporadic.

Anyway, question for this topic is regarding the engine oil. I checked the level with the oil dipstick and that's ok, but there is what I would call smudge/residue built/caked up on the stick, oil color is very brownish/black, so in my eyes it's been overdue an oil change for some time now. The car hasn't been driven for about 5 months.

I would really like to get the engine as clean as I can without spending too much money on it, so I've been thinking if I could add some kind of cleaning additive to the oil already in the engine, have it do it's magic for however long it should, then drain the oil and put in new full synthetic oil/oil filter. Any recommendations as to this approach?

Would using the Bosch Super 4, FR78 spark plugs be a good idea, or should I just stick with the Volvo spark plugs. I'm not looking for more power, however increased mileage wouldn't be bad.

Thanks, Teddy

[erikv11]

The multi-prong electrodes in general work very poorly in these engines. Stick with the OEM plugs or something simple like simple Bosch copper FR7DC.

Lots of people use Seafoam in the oil but I haven't, so have no opinion on that one.

[abscate]

Velkomst Teddy!

I've had success with a product made by Bell Engineering for desludging turbo VW engines. I'll find a picture and send link.

http://www.klmperformance.com/bell-perf ... mover.html

I would replace the oil with synthetic right away, then replace again in 1000 km driving. If you choose to use the desludging, you put that into the cold dirty oil, idle the engine for 10 minutes, then change it

[Teddy1975]

Thank you both.

I'll go for the Volvo OE plugs and 5W40 oil with a desludge treatment first.

/Teddy

[misha]

Your signature is wrong.There is NO 2001 S70!
Last model year was 2000.

[Teddy1975]

Hi Misha.
You're absolutely right. My only excuse is that I had that car back in 01 and somehow got that mixed up with the year the car was from. It's from 99 at least according to the Swedish motor authorities. (I lived in Sweden back then).

[misha]

I mentioned that just to avoid confusion.

Welcome aboard!

[precopster]

Multi -prong spark plugs are OEM for this car however they are expensive. I've used OEMs in my own car (2000V70 non turbo) for over 49,000kms. I've searched the NGK range and found 3 prong plugs with the same heat range and used BKR6ETUC in a customer's 99 V70 non turbo for over 30,000kms with no problems.

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When a car has too much carbon/sludge in oil I'll use an oil flush product that usually goes in 15 minutes prior to oil change and then drain. After that I'll pour about a litre of Shellite (pure hydrocarbon) down the oil filler hole which will assist with desludging the valve area. It will pour straight down the oil galleries and into the sump and straight out of the drain hole. After that I'll pour about a litre of cheap mineral oil down the oil filler to get rid of the hydrocarbon liquid sitting around the valve area. Again that oil will drop out of the sump plug hole.
Then fit drain plug and top up with synthetic or oil of your choice.

I did this to numerous customer's cars and my wife's 2002 XC70 which had over 400K kilometres and it is still keeping the oil very clean between changes.

[erikv11]

Ah, yes, I meant multi-prong NON-VOLVO plugs are bad news, sorry, and that you may want to go with Bosch coppers if you are not buying OEM. Listen to Mike, I have no arguments with his post.

[cn90]

I don't know if you can get NGK Iridium in Denmark, but give it a try.

I installed the NGK Iridium BKR6EIX in my Volvos (1998 S70 and 2005 XC90).
Great spark plugs, good for 80K-100K miles.

Detail below...

DIY: 2005 XC90 2.5T Spark Plugs using NGK Iridium BKR6EIX
https://www.matthewsvolvosite.com/forums ... hp?t=64080