I do my own service work and I have a 93 940 with about 200K on it. I was about to change my oil and realized I didn't have a Volvo filter so I bought what I consider a good quality filter. I had a case of 5W30 synthetic oil so I used it. After that when I start my car it was a good 5 seconds before the pressure built up and it used about a quart every 5K miles. I bought a Volvo filter and 10W30 organic oil and changed it again and now no oil consumption and no time lag for oil pressure. I never believed there was such a difference in filters and oil but now I know.

 

wow.....good to know

 

I'm thinking that you might have been losing some oil around the filter. Just because you switched to synthetic oil you shouldn't have started using that much oil. I have been using synthetic oil in my vehicles ( Oldsmobiles, Fords, Jeeps, Chevys, Toyotas, Volvo) for at least 10 years and never had one use any oil. There had to be something else going on to have it suddenly start using oil.

 

The OE German-made Mann filters have the by-pass & anti-drain back valves specified by Volvo. With almost every aftermarket filter that I've tried, there's a delay in oil pressure on cold starts(Purolater Pure One being the only exception...but they're priced about the same as Mann).

 

Not my work but a great study on Filters by a engineer.

Oil Filter Rankings
1. Mobil 1 (expensive)
2. Purolator Premium Plus
3. Pepboy Proline (same as PPP)
4. Napa Silver or Gold
5. Motorcraft (PPP based)
6. AC Delco Duraguard
7. All Frams

Note Fram is bottom feeder, cheapest materials and shoddiest construction,
but everyone likes the orange paint. I buy #2 at Autozone for under $3.