i am going to do a service on my work car(vw caddy 1.9 sdi 1999). My question is... What engine oil grade should i use 10w40 or 15 w40. In my country during the summer the temperature goes up to 30 grade celsius and during the winter the temperature goes to -15 or -20 grade celsius. And what kind of oil should I use full synthetic or semi synthetic. Also what do you think about these brand oil: Profi Car oil and Addinoil(zeller+gemellin) both branda made in Germany. Thank you!
According to Car.info, your Caddy can use 0W-30, 0W-40, 5W-30, or 5W-40 synthetic oil, or 10W-40, 10W-50, or 10W-60 in a semi-synthetic version.
You talk about the temperatures of either 30°C (86°F) or down to -15 to -20°C (-4°F). Neither of these are what I'd call extreme. Because of this, my recommendation to you would be to run the 5W-30 synthetic year round. You shouldn't have an issue with either the hot side or the cold side of where you live.
Typically, a 5W oil is recommended for winter use, but synthetic oils can be formulated to flow even more easily when cold. This way, they are able to pass tests that meet the 0W rating.
If you are choosing to run synthetic, you should not have any issues.
As far as a brand of oil goes, I'm not going to recommend one to you. The reason? We don't do that here. If you buy a major brand (for your country) full synthetic, you really shouldn't have an issue.