If that is OK, you need to check the thermostat to make sure that it is opening. Find the lower radiator hose and check
how hot it is compared to the top hose. If it NEVER gets hot, then the thermostat is not opening or the water pump is not
If it DOES get hot, but the fans don't come on, you need to check the fans. However, fans are not required when driving
at a constant speed... so if it overheats while driving at steady speeds, then it is not a fan issue.
The oil light issue might be related to the overheating... oil gets thinner when it gets hot, so it does not produce the same
1.8T engine or 2.0L engine? If 1.8T, you could also have a restriction in the oil pick-up screen in the oil pan.