This is my (probably very incomplete) summary of a bunch of threads here on BITOG regarding optimum practice for longest timing chain life.
Desirable Properties of Oil:
- As thick as possible for hot operating conditions (i.e. xW-40 > xW-30 > xW-20)
- As thin as possible for cold-weather starts (i.e. 0W-x > 5W-x > 10W-x > 20W-x)
- As little viscosity spread as possible (i.e. 5W-20 or 10W-30 > 0W-20 or 0W-30 or 0W-40 or 5W-30 or 20W-50)
These properties are somewhat contradictory - an oil that's both thin enough for cold weather and thick enough for hot weather will have a large viscosity spread.
My compromise is to use 5W-30 or 10W-30 for the summer, and 0W-20 or 0W-30 for the winter.
Bear in mind I do live in an extreme climate, where we saw -40 C (-40 F) in February, and are now seeing 37 C (99 F) in early summer.
The other thing I've picked up is that clean oil is essential for minimizing timing chain wear. This might be much more important than viscosity. With that in mind, I try to keep up with the air filters too.
I service three vehicles - a 2007 Dodge Grand Caravan 3.3 (which specs 5W-30 year round), a 2009 Mazda 5 2.3 (which specs 5W-20), and a 2009 Kia Sedona 3.8 (which specs 5W-20 on the oil filler cap, but in the owner's manual specs 5W-20 or 5W-30 year round, or 10W-30 down to -20 C [-4 F]).
The Dodge is cam-in-block, with a short timing chain. I don't worry about it much.
The Mazda is DOHC, but one bank only, so again the timing chain, while longer than in the Dodge, is still fairly simple.
I worry about the Kia, with its long complex chain driving four camshafts. So far, so good though.
Thoughts?
Desirable Properties of Oil:
- As thick as possible for hot operating conditions (i.e. xW-40 > xW-30 > xW-20)
- As thin as possible for cold-weather starts (i.e. 0W-x > 5W-x > 10W-x > 20W-x)
- As little viscosity spread as possible (i.e. 5W-20 or 10W-30 > 0W-20 or 0W-30 or 0W-40 or 5W-30 or 20W-50)
These properties are somewhat contradictory - an oil that's both thin enough for cold weather and thick enough for hot weather will have a large viscosity spread.
My compromise is to use 5W-30 or 10W-30 for the summer, and 0W-20 or 0W-30 for the winter.
Bear in mind I do live in an extreme climate, where we saw -40 C (-40 F) in February, and are now seeing 37 C (99 F) in early summer.
The other thing I've picked up is that clean oil is essential for minimizing timing chain wear. This might be much more important than viscosity. With that in mind, I try to keep up with the air filters too.
I service three vehicles - a 2007 Dodge Grand Caravan 3.3 (which specs 5W-30 year round), a 2009 Mazda 5 2.3 (which specs 5W-20), and a 2009 Kia Sedona 3.8 (which specs 5W-20 on the oil filler cap, but in the owner's manual specs 5W-20 or 5W-30 year round, or 10W-30 down to -20 C [-4 F]).
The Dodge is cam-in-block, with a short timing chain. I don't worry about it much.
The Mazda is DOHC, but one bank only, so again the timing chain, while longer than in the Dodge, is still fairly simple.
I worry about the Kia, with its long complex chain driving four camshafts. So far, so good though.
Thoughts?