I notice a tapping sound from engine after full synthetic oil change. Is this normal. I've used a sythetic blend in the past. Also I'm a little overfilled indicated bt dip stick. I'll drain about 1/4-1/2 pint off. Hope this quiet it down. This only happen when I'm idled for a period of time.

From 1997 960 Owners manual:

B 6304 S Engine
This engine features hydraulic valve lifters which means that valve clearance is adjusted automatically. It is possible that the valve lifters will produce a ticking sound for the first few seconds after the engine is started, while the oil pressure is increasing.
If the car has not been used for a long period of time, this ticking sound may last for up to 15 minutes. This is entirely normal.

NOTE: Do not exceed 3000rpm until the ticking sound disappears.

Do not use oils with other viscosity ratings. The use of incorrect viscosity oil can shorten engine life.
Volvo recommends the use of energy-conserving oils. Look for the API label. Synthetic oils complying with oil quality requirements are recommended for: driving in areas of sustained temperature extremes (hot or cold), when towing a trailer over long distances or for a prolonged driving in mountainous areas.
Extra oil additives must not be used unless advised by an authorized Volvo retailer.
SAE 15W/40 is recommended for use in driving conditions that raise oil temperature and increase oil consumption (i.e., mountain driving; trailer towing).

I run Mobil 1 10w30 in my 97 960 (84k Miles) There no oil use issues what so ever. Oil changes are done every 6K miles with no additional oil added between changes. The engine is extremely quiet after it warms up. Like all 6304's it has the valve tapping noise when cold.

Do not use full sytetic oil of any weight in these cars. Syntetic blend is OK.
I use Dyno Oil, is what these cars are designed for. I change Oil every 5,000 miles and filter evry 10,000 miles. Full syntetic oil is to thin for these engines. If you park your car for a week or two, when your start that engine is going to sound like the cylinder head is going to bust through the hood.

This no longer happens since I've been using M1 5W40.

DEWFPO
--
1998 S90 077,400 and 1995 964 154,100

I am afraid your information is incorrect. Volvo (like most manufacturers)recommends synthetic oil in the S90, in fact in all their vehicles. It is normal to hear slight valve noise upon starting engine cold. Synthetic oil is available in all the same viscosities (thickness)as the old dyno oil and any blends.

If your car sound like a cylinder head is coming through the hood you have serious problems that no amount of any type of oil will solve.
--
David Hunter

Those were the recommendation from a mechanic specialist in Volvo, BMW, Rolls Royce and Ferrary. I had to believe him. And I still do. Syntectic oil is for race cars. If you want, I give you his phone number.
But, anyway opps! sorry for wasting your time or anyone else.

Are you using 5 or 10W30?

This seems normal for these engines when hot. The only way I have been able to keep mine relatively quiet is to run synthetic 5W40 and occasionally perform a high rpm run.

DEWFPO
--
1998 S90 077,400 and 1995 964 154,100

Notice that Volvo does nor reccommend the 5W-40 oil, or in general anything with a large spread between the two numbers. But I do agree that the high rpm once in a while can help.

S' V'

Yes I've notice that after a run its all quiet. I'll change the weight next time and compare.

If the problem persists you may want to consider dropping your oil pan and resealing the oil pickup system.

Mark