I'm not sure that 2 stroke oil would be necessary in our oil-lubricated Mercedes IPs-but, I've run it in my Cummins powered Dodge's fuel-lubricated VP44 IP, already lost one under warranty (due to internal binding/timing issues), next one's mine to buy. I'd like to hear from some of the high mileage 123 owners-how many have had IP problems of any kind ever, mine is at 164K now, other than a new primer, filters, and an occasional diesel purge appears original, I would hate to risk causing a problem where there isn't one now (got enough things to fix already...).

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1982 300DT 190K (Diesel Purge + synthetic oil=smoothness at last!!!)
2004 Ford E-350 6.0 L PSD 227K
2006 Dodge Ram 3500 SRW HO Cummins 4X4 48RE 42K (brute force tow vehicle)
2005 Scion xB wife's rolling pop can
1993 GMC Sierra C3500 6.2 142K