Oil Confusion

[John D]

OK - I'm confused(not a rare event I assure you). I have a Volvo MD7a and the manual calls for a diesel grade oil of 20 wt for over 10 degrees C (which is about 55 F I think). I can't find any such oil. The inputs so far have been "use 30 weight, 20 is too light anyway" and "15-40 is the same as 20 weight". This is the forst time I've changed the oil and it appears the previous owner may have used 30 wt as there is a partial jug of Haveline 30 wt there. I live in the Seattle area and although you could rarely describe it as tropical, it does, on occasion, get above 55 or so. What is the correct weight to use? How much does it matter? Any input is appreciated.

Thanks

John D
S/V Mariah



john_dupras@hotmail.com

[Bob Pence]

OK - I'm confused(not a rare event I assure you). I have a Volvo MD7a and the manual calls for a diesel grade oil of 20 wt for over 10 degrees C (which is about 55 F I think). I can't find any such oil. The inputs so far have been "use 30 weight, 20 is too light anyway" and "15-40 is the same as 20 weight". This is the forst time I've changed the oil and it appears the previous owner may have used 30 wt as there is a partial jug of Haveline 30 wt there. I live in the Seattle area and although you could rarely describe it as tropical, it does, on occasion, get above 55 or so. What is the correct weight to use? How much does it matter? Any input is appreciated.

Stick with 30W. Use on of the three best, Chevron Delo 400, Shell Rotella or Texaco Ursa. After selecting a brand, stay with it. Each brand has slight differences. Changing invites gumming etc.

Thanks

John D
S/V Mariah

sixpence@dmv.com