Pennzoil does indeed make a 15w40 diesel oil. I see it at WallyWorld occasionally.

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Palangi

2004 C240 Wagon 203.261 Baby Benz
2008 ML320 CDI Highway Cruiser
2006 Toyota Prius, Saving the Planet @ 48 mpg
2000 F-150, Destroying the Planet @ 20 mpg



TRUMP .......... WHITEHOUSE
HILLARY .........JAILHOUSE
BERNIE .......... NUTHOUSE
0BAMA .......... OUTHOUSE

I think that is an old wives tail. Any leaks you have will not change with synthetic. I think stories of engines leaking come from the synthetic cleaning out the crap that had been helping the old dried out seals to leak. Any engine in good shape should have no problem switching at any mileage. I have been running synthetic since I got my car and no new leaks.


btw I switched from Mobil 1 15w-50 to Delvac 1 5w-40. I think I am going to go back to 15w-50. My hot oil pressure ie after a long highway run with the AC on drops to 1 bar with the Delvac 1. The oil pressure was .25-.50 bars better with the thicker oil.

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2016 Corvette Stingray 2LT
1969 280SE
2023 Ram 1500
2007 Tiara 3200