Mobil 1: Mixing Viscosities = ?

[Doug H]

Hello Patrick,
the Delvac range of lubricants is tailored for Commercial use. I have extensive experience with Delvac 1 5w-40 engine lubricant in a variety of engine families and for around a decade or so. Its close relatives were/are M1 SUV 5w-40 and M1 Turbo Diesel Truck 5w-40. It is a Group 4/5 lubricant with around 25% ester content

I used it in all of my Series 60 Detroit Diesel engines (12.7ltr, 500hp, 1650ft/lbs) over many years. I averaged 60k (miles) OCIs using Used Oil Analysis. I authorised a tear down inspect on one engine after 1m kms (620k miles) and all wearing parts met Detroit's reuse parameters. Hone marks were still visible on the wear surface of each liner

I used Delvac 1 5w-40 in my MY89 928S4 for around 50kkms over five years. Ten UOAs were progressively published on another Forum. I will publish the last (No 11) when I get the results in the next week or so if you wish

I also use it in a wide range of other petrol engines and it was in my MY98 2.8 Z3 BMW for around 60kkms

It is not an Approved Porsche oil as it is a mixed fleet HDEO. It would exceed all of Porsche's test protocols

Many believe that it (Delvac 1 5w-40) is one of the best engine lubricants ever made and my experience tends to confirm this

I have no affiliation with any Oil Company

Regards
Doug