If it matters, my Jeep's 4L is performance enhanced like Lance Armstrong, but without the legal issues and shame. Haha
I assume both diesel/gas rated and Euro rated 5W40 are more than good enough for my Jeep 4L.
So whichever is widely available at most stores and is cheapest maybe the way to go since both are likely better than my Jeep needs. That's why I'm seriously considering Shell Rotella T6 5W40 and Chevron Delo 5W40. In my local area they are the cheapest 5W40 and are available at every auto store and Walmart.
I know Rotella is good for Jeep 4L because it's super popular at all Jeep forums with 4L engine users, and even more popular at Jeep stroker forums (where they hop up 4L engines into performance 4.6 or 4.7 strokers).
I like Penzoil Euro 5w40 just fine and I'm sure it's more than good enough. My engine runs noticeably quieter at all op temps and cold starts easier in cold weather than with any 10W30 conventional I ever tried. Also, 5w40 has the same good oil pressure at idle at full op temp as 10W30 conventional had. 10W30 synthetic had slightly lower oil pressure at idle at full op temp and more engine mechanical noises (valve train especially) so I won't 10W30 synthetic anymore.
I never tried 5W30.
I have used 0W40 Mobil One. My engine didn't like it. It blew a little blue smoke at startup (which it didn't do with any other oil) and after 3000 miles use on the oil it apparently lost some viscosity because my oil pressure became lower at idle at full op temp.
I've used Mobil One 5w40 (turbo diesel) and Penzoil Euro 5W40 and my Jeep 4L engine loves them both. However, those are expensive oils. Shell T6 Rotella 5W40 is 1/3 lower cost (in my local area) and Chevron Delo 5W40 is lower yet. Rotella and Delo are the lowest cost 5W40 available in my area, and both are good brands.
Sometimes Valvoline Synpower 5W40 is on sale cheap. I've never tried it. Is it a Euro oil? If so, how good is it?
Is there a Valvoline Maxlife 5w40? is there any brand of high mileage 5W40?
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Below is more specific info about how I use my Jeep and change oil.
I use a Baldwin B2 filter (twice as long as normal filter, all other filter specs same as normal). The B2 filter holds 1 quart of oil. So my 4 liter engine + filter holds 6.5 quarts.
I want:
Lowest possible wear rates.
Good cold start protection.
Good protection at high op temps.
Good anti-foaming protection for when I run at or near 5500 rpm red-line passing cars going up mountain passes. No driver safety lectures please. It's one of my few pleasures in life and I'm 48 and have never caused a wreck.
My driving is a mix of level(ish) city and highway driving (when going N/S), and mountain highway driving (when going W/E).
I change my oil every 2 to 2.5 years (when it reaches 5000 miles).
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I'm sure Penzoil Euro 5W40 is exceeding my needs, but a 5W40 by Shell Rotella, Chevron Delo, or Valvoline Synpower might also exceed my needs while costing much less.
Delo 5W40 is the cheapest 5W40 (in my local area anyway). How good is Delo 5W40 compared to Shell T6 Rotella 5W40? Are there any valid comparison tests/lab tests of the two that I could look at? How good is Valvoline Synpower 5W40? Those are the 3 oils I'm considering using because they are widely available (in my local) and much cheaper than Penzoil Euro.
However, I'll continue paying more for Penzoil Euro 5W40 if anyone can point out any benefit over those others.
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P.S. - In hindsight, I should have typed this post for my OP.