I logged over 275,00 miles on my 2005 (LLY) Duramax using Shell Rotella T3 (now T4) with very good UOAs. I live in MN and would often see cold starts in the -10 to +20* F range. Thankfully I usually parked in a attached garage which helped with the morning start, but the afternoon one was always at ambient. I never really noticed a hard starting condition, but I will say I did frequently see oil pressures in the 100+ PSI range. I also took care to not work the truck hard or fast until things got a little warmed up, but I am also not one to sit and idle - that just wastes fuel.
I don't really care about the synthetic vs. conventional debate. If there was a dino oil that was 5w40, I'd already be using it. The only reason I am considering changing to 5w40 is for cold starting and emissions systems. I recently sold my 2005 and now have an 2018 (L5P) which is fully emissions compliant. I am thinking using a thinner oil will aid in keeping the DPF cleaner longer during winter time. I haven't seen much data around this topic with an emphasis on cold starting and emissions. I am not worried about wear metals or extended drain intervals, with the Duramax it simply doesn't matter.
Does anyone have any first hand experiences with switching to 5w40 purely for emissions or cold starting?
I am hoping @dnewton3 is able to chime in on this one too. He has more experience with this engine and different oil viscosities than anyone.
I don't really care about the synthetic vs. conventional debate. If there was a dino oil that was 5w40, I'd already be using it. The only reason I am considering changing to 5w40 is for cold starting and emissions systems. I recently sold my 2005 and now have an 2018 (L5P) which is fully emissions compliant. I am thinking using a thinner oil will aid in keeping the DPF cleaner longer during winter time. I haven't seen much data around this topic with an emphasis on cold starting and emissions. I am not worried about wear metals or extended drain intervals, with the Duramax it simply doesn't matter.
Does anyone have any first hand experiences with switching to 5w40 purely for emissions or cold starting?
I am hoping @dnewton3 is able to chime in on this one too. He has more experience with this engine and different oil viscosities than anyone.