Rode in my friend's 2006 GMC Duramax pickup today. Oil pressure gauge shows 0-120. Start up pressure was 60. After warmed up, pressure at 60mph was 30 lbs, sometimes 25. No higher than 30psi with high rpm's taking off from a stop. Idle pressure showed around 5psi. I didn't say anything but this seemed low to me. Anyone know if these are appropriate pressures on a Duramax? My intuition was that these pressures seem low and if it were mine, I'd confirm the gauge was accurate and if so find out why the pressure was low.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13