Oil Viscosity

[Koya]

I was looking around the site and found a post with a member changing the oil viscosity for the 5w-20 to 5W-30. I've seen the 5W-30 used a lot on Chevy small and on a lot other car makers.

What side effect one will encounter going to higher viscosity? Since I do not know what type of oil was used before I got this SUV, I would like to switch to full synthetic (Mobile 1). Is there a side effect going synthetic from the conventional oil?

 

[jt_armstrong]

There is a side affect in your wallet. Sure you can stretch the miles between oil changes but I still think a good quality mineral oil changed a regular frequencies is as good as you need.

 

[rice_classic]

There's no side effect. In fact, you'd be doing your engine a favor by choosing a 0W-20 or 0W-30 because the majority of wear occurs during start up and having an oil with a slightly thinner cold-viscosity reduces that. (your hot viscosity will be the same/similar as your OEM 5w-20 of course).

I run 0w-30 in my Expy (over 150k miles) which I tow with and I specifically use a Synthetic due to the greater shear stability and thermal stability inherent in it which is important when pulling 7500lbs on a 95F day. Synthetic is pretty inexpensive nowadays. Mobil1 5qt jugs at Walmart are usually <$30 and now I'm comfortable changing my oil every 5k miles instead of 3k under hard use.

YMMV.

 

[Koya]

There's no side effect. In fact, you'd be doing your engine a favor by choosing a 0W-20 or 0W-30 because the majority of wear occurs during start up and having an oil with a slightly thinner cold-viscosity reduces that. (your hot viscosity will be the same/similar as your OEM 5w-20 of course).

I run 0w-30 in my Expy (over 150k miles) which I tow with and I specifically use a Synthetic due to the greater shear stability and thermal stability inherent in it which is important when pulling 7500lbs on a 95F day. Synthetic is pretty inexpensive nowadays. Mobil1 5qt jugs at Walmart are usually <$30 and now I'm comfortable changing my oil every 5k miles instead of 3k under hard use.

YMMV.

Thank you! If 0w-30 is good without any side effect. What about 0w-40? Our BMW 650i takes 0w-40, I will tow but not as often than most. This is my daily driver also.

 

[Red92lx]

I use a 5w-30 Mobil 5000 or Pennzoil yellow bottle (which ever is cheaper) and have had good luck so far. I also use a good filter (Motorcraft or Purolator). I know ford claims a 5w-20....but I would rather use a 5w-30.

 

[rice_classic]

Thank you! If 0w-30 is good without any side effect. What about 0w-40? Our BMW 650i takes 0w-40, I will tow but not as often than most. This is my daily driver also.

Engine is designed for 20. I'm only going 30 due to the heat I will occasionally endure while driving across the state in the summer with a 7500lb 20' box behind me.

I can't say definitively if a 40w is good/bad/indifferent but I would guess it's unnecessary. It's the not the thickness of the oil that's doing the protecting. The reason for the 30w is that I will be putting additional temperature into the oil such that my 30w (at that temp) will be the roughly the same thickness as the 20w would be at it's intended operating temp. Therefore if I were to increase the oil temp such that a 40w would be necessary then everything's probably too damn hot already.

I hope that makes sense.