Hi there going to do a service on my new bug wrx it has a 151k on the original engine.
I have some comma 5w50 to go in this should be OK? ?
If not what's my best option.

Cheers

 

5w would be too thin at that milage be better with a 10w50

 

5w wouldn't be too thin. It has the same viscosity as a 10w but its operating temperature is lower. The max number 40 or 50 is where the oil will thin out due to heat.

 

Hi

It's probably not the worst thing, but a 5w-40 would probably be the best choice.

The lower the first number, the thinner it is when cold. Often, the thinner the better as it flows faster for better for cold start protection, the only issues is that a badly worn engine or one with larger tolerances might sound a bit rough with a thinner oil when cold.

The second number refers to how thick the oil is at 100C, the higher the number, the thicker. You want the right viscosity as too thin or too thick leads to reduced protection. A 40 is fine for most Imprezas, unless heavily tuned or badly worn.

Cheers

Tim

 

As Oilman says, cold start is just as important if not more for a high mileage engine. I have 157k on my blob atm using 5w-40 fully synth with no problems. Have done for the past 4 changes. If that helps.