Why I add 12% (one gallon) of gear lube at every oil change...

[jmartin]

I am also wondering if it is ok to run in a mandated engine. I have a vehicle with a 3.0L diesel that has EGR DPF SCR and the OEM oil spec is low saps. I’m suspicious that low saps oil along with stupid long intervals is a major factor in timing chain wear these engines are known for. Would running Rotella T6 15w40 with 10% GL5 gear lube be ok in this engine or is the design and materials of a euro 3L too different from an ISX?

My other idea is to just use Motul 8100 10W60 since I can get it for a good price. It is “full saps” so it should offer better wear protection.

The OEMs say you must use low saps or your DPF will get ash loaded quickly. Is it really a big issue? If the engine is in good condition and you run a higher viscosity oil you should not be pushing much oil through the DPF thus limiting ash deposits, correct? Also, I wonder if the excessive OEM change interval lengths lead to the viscosity breaking down and getting burned via blow by and crankcase ventilation, hence the need for low saps. This would be compounded by the 5w30 or even 0w20 spec that light duty diesel oems are calling for these days.

Looking for opinions... At the end of the day, the goal is to protect the timing chains without ash loading or compromising the dpf prematurely.