yes, i searched, this has never been addressed before (that i could find).

ok, i need to change my oil and im going to switch to synthetic (mobil 1). up till now ive been running pennzoil 5w-40, but they dont make mobil 1 in that.

in my search i found that the two most popular Mobil 1 weights here are 15w-50 and 0w-40. the first for its better protection, the second for its easier cold startups. but i live in houston and its the summer so sub-zero startups will never be an issue.

the reason i cant decide is because unlike most diesel drivers, i usually only put about 5-10 miles per day on my car. my commute is very short and i almost never have time to let my engine warm up. however, i do occasionally take very long road trips.

my question is, which weight oil is better for short trips running in a cold engine, but still provides good protection for long trips in 95F+ weather?


please try to stay on topic for everyones sake.

thank you.

__________________
1991 300 D 2.5 Turbo, 220k
also in the family:
1981 240 D 185k
1991 350 SD 185k
2006 S 500
2005 SLK 350

they actually have rebadged what is quite possibly the best oil out there, (mobil delvac 1) 5w-40, and now sell it as a mobil 1 product: mobil 1 truck and SUV 5w-40.

Thats what Id use.

Otherwise, probably rotella 5w-40 synthetic. Technically not a real synthetic, but the price reflects it (13/gal), so I think its great stuff.

JMH

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Current Diesels:
1981 240D (73K)
1982 300CD (169k)
1985 190D (169k)
1991 350SD (113k)
1991 350SD (206k)
1991 300D (228k)
1993 300SD (291k)
1993 300D 2.5T (338k)
1996 Dodge Ram CTD (442k)
1996 Dodge Ram CTD (265k)

Past Diesels:
1983 300D (228K)
1985 300D (233K)

Delvac-I is the best oil for short trips as it isnt prone to breakdown. If that is too costly, I suggest Delo 400 as a good alternative as well as Delvac Super.

15W-50 is fine. Synthethics flow better at low temps so in your climate there is no need for a thinner oil. The harm in the short trips will not be from too thick oil but rather carbon build up and possible condensation in the crankcase due to the engine noy getting to full operating temp. Do yourself a favor and at least once a week take her out for a good, spirited 20-30 minute drive to let everything get nice and hot and blow the carbon out.

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LRG
1987 300D Turbo 175K
2006 Toyota Prius, efficent but no soul
1985 300 TDT(130K miles of trouble free motoring)now sold