BACKGROUND: This is the first used oil analysis on my 2002 Infiniti QX4 (four wheel drive). The truck had 45,000 miles on its VQ35DE engine and 6,796 miles on the oil (Shell Rotella T 5W-40) when this oil sample was taken. It saw pretty hard service this past year. I normally put most of the miles on it during the ski season, and the rest of the year it gets used only on weekends for shopping or camping trips. I didn't get to do much skiing or camping last year, so it usually saw only short trip service on the weekends. That's tough on any oil because the oil doesn't get hot enough to burn off all the contaminants during short trips.
Towards the end of the year I decided to do an Auto-Rx cleaning. Auto-Rx had done well in my motorcycle and I figured it'd be good to get the truck's engine cleaned up as well. This analysis is of the oil with the Auto-Rx in it. I've been using Mobil 1 oil filters (standard, not the new extended use ones), and for this OCI I reverted back from a K&N air filter to the OEM paper air filter. I also started using FP60 during the last three months/1,500 miles of this OCI. There was no improvement in overall gas mileage that I've been able to discern, nor any other effects. However, I own a lot of it so I'll keep using it and see if there's any gradual improvement.
The four OCIs prior to this one I'd been using Mobil 1 5W-30, so that explains the little bit of moly detected. (This engine keeps about two quarts of oil hidden in areas that don't drain down into the drain pan, so there's significant carry-over from one oil change to the next.)
I now have a fresh fill of Rotella T 5W-40 in it for the Auto-Rx rinse phase. I'll run 3,750 miles on that oil then switch to Castrol Syntec 0W-30 (German Castrol, or GC for short) to work towards 7,500 mile/1 year OCIs on the GC.
ANALYSIS: Between the very high levels I've been seeing in my motorcycle, and my worry about running this oil for almost a full year, I thought that the analysis looked pretty good. The oil held up quite well, staying in grade without any significant change in viscosity and it still had plenty of TBN left to handle the acidic byproducts from short trip service. Those were my main concerns, and if I hadn't bought a lot of GC oil already I might be tempted to stick with the Rotella.
However, there's a reason I pay for professional analysis of the results. Terry Dyson reviewed these results and from the elevated Si/Na identified a significant leak somewhere in the intake system causing elevated wear. Argh! My personal hope is that Terry's just seeing the residuals from running a K&N for quite a while, which we know allows more dirt to get past in many cases. However, the intake behind the air cleaner doesn't seem dirty, so maybe the air is leaking in from somewhere else.
So, it's not going to hurt to go over the system with a fine tooth comb and see if I can find anything amiss. I've ordered air filters from Fram, AC Delco, Wix, and Purolator to see see if any of them provide a better fit than the OEM one. I'll also examine all the fittings in the intake system and the PCV valve.
While it is certainly better to know that I have a problem so that I can fix it, I'm disappointed to learn of it. I really hope to hang on to this truck for a long time (more than ten years) to further other financial goals. I don't want the engine wearing out early because of poor air filtration!