Proud new owner of a 98 v770 wagon! 236000km, FWD, no turbo but it has a 5speed, only one I've ever seen. Car runs good, has been well maintained, burns no oil and has zero rust or dents. It threw a few codes after I started driving it and I've had to replace the ABS module (Midwest, great service) and just today the coolant sensor code came up. So I ordered the sensor and was going to pick up antifreeze tomorrow to change it out, when I noticed the sticker saying use only Volvo coolant witch is type C and is bluish colour. the newer yellowish type D is in it now and has been since the radiator was replaced a few years back. Is this ok to use or should I drain it and change it out to the older style? In the next little while I plan on doing the timing belt
and a tune up and I'm wondering: change PCV valve? (50000km since last done) Clean or change o2 sensors? Since I want to keep this car for a while, is there any other parts that I should check or replace as a matter of course- especially sensors? thanks.

 

Awesome! I would love to have a 5 speed wagon. I have or had several 98's, and I would say the maintenance routine is best described by watching some of RobertDIY's youtube videos. There is a sticky post on 850's "what to do when I buy one" that is great. The big threat to them is the heater core, or anything that causes overheating, and the timing belt. The PCV has to be done once in a while, but 50,000 km is not so much. Search for the "glove test" here and consider making a blow-by test that way. For OBDII cars, like this, I think you learn a lot more from actual data than you do from codes. For instance, you can just read what the engine temperature is and decide whether you agree or not. With this you can find problems with the temperature sensor long before the computer, which has nothing to compare that temperature with, can set a code.


Yellow HOAT antifreeze is good, I think. You will only lose a teacup full of coolant changing the temperature sensor, so I guess it would make sense to consider whether you want to add anything other than water back.

 

regarding the O2 sensors - I would not change them unless they fail - or if you are needing to replace the cat or downpipe. They often get blamed for problems that are actually upstream such as air leaks or poor tune. You should never have to clean an O2 sensor either.

Regarding coolant choice - a good rule of thumb on older white blocks is green/yellow = good, orange/red - not so much... and don't mix colors. The Dex-cool types may corrode any yellow metals and solders in the cooling system in older cars, where newer cars have mostly aluminum. Unless you have overheating problems, if you decide to do a flush, keep it simple and use distilled water for the flush then refill with 50/50 green. It doesn't have to be Volvo brand. If you feel a need to do a bit more, check out some citric flush products.