Preferred Oil / Weight

[cruiser54]

I might be mistaken as I do not work in the oil industry, but I always though multi viscosity oils were made from stock with a viscosity of the first number, using friction modifiers to act as the second number at 100 degrees Celsius (about 210 Fahrenheit). So a 10W30 is made from 10 weight oil with viscosity modifiers to make thin out only as much as 30 weight when hot.

 

Multi viscosity oils still thin out as they get hot, and still do so as a logarythmic function of temperature, but with a flatter curve than a single weight oil.

 

That's what I always thought, too. But some people have said that's wrong.

[danbyrambler]

MVUSSE - I didn't work in that area either - - I was educated about motor oils back when by 2 friends who are petroleum engineers - actually 3 of them, but Mike went on to get a phd in chemistry & focused on industrial water treatment - Regardless, They set me straight on all the multi-viz BS I'd gleaned from Popular Mechanics, Motor Trend & the like - Bob & Don worked in sales for Shell & from them I learned of rotella - used it in my '56 T-Bird & continued on with it - - - Anyway, it is the 2nd # that is the base stock - -

 

EAGLE - - No oil flows well when cold - viscosity is resistance to flow at temperature - I've forgotten where the viz chart stops-can not be measured-on the frigid end - ditto for the other end when it starts to burn - - anyway, I'm old enuff 2 remember also - Used to buy oil at a scratch & dent for 6-7 cents qt as a kid/college student & cried when all they had was the 10-12 cent stuff - - - Also believe we have Japan to thank, more than anything else, for engine longevity or at least they forced Detroit to get real with things - - Helped a friend replace a head gasket on his 175k or so Honda IIRC, back about '81-'82 & was thunderstruck at the almost compleat lack of a cylinder ridge - wizardry? - Nah, just better mfg materials - put my reamer away & used the hone to remove the mostly carbon ring from the 4 holes - b4 then I knew 50k to 80-90k hone time mostly & over 90k reamer 4 sure - no bout a doubt it - - - The miracles started with the Demming award/prize/method - Part of the Marshall Plan

 

HORNBROD - - Good 2 know about the CHEVRON & it's zinc content - - Guess I'll be making a switch

 

END OF LECTURE - - VIYA CON HUEVOS! :thumbsup:

 

[xjrev10]

Rotella and WIX! Summer 15w40, winter 10w30. Always top off the oil when I fuel up and most of the time its 15w40 cuz its available at the truck stop where I always buy my fuel.

 

Seems to be a popular combo. Once in a great while I might use a mopar filter.

[huck731]

a few articles to help out.

 

http://www.upmpg.com/tech_articles/motoroil_viscosity/

 

when I find the other one I am looking for I will post it. It was written by an engineer who did 72 hours of research and wrote a huge paper on how oils work and everything in plain english. related oil weights to melted candle wax.

[Stew0958]

I have read all of the posts, and am still confused.  My husband passed, leaving a 87 Jeep Comanche to my grandson...and no manual or instructions.  He will be getting it soon for his 16th birthday and I want to make sure it is ready to go.    I am not sure of the miles...it's parked in a storage facility.  Should I fuel up with High-test (premium gas)?  Can I get a consolidated bit of advice on the oil to use?  Please keep in mind that I just want the kid to have many more years to remember kicking around with papa in that jeep.  Thank you all so much for your expertise and advice.  Regards, Stew  

[87MJTIM]

The factory recommended oil is 10w-30.  However, other owners use Shell Rottella oils for its higher zinc content.  Oil manufactures have changed the chemical composition in 35 years.  Using oil with higher zinc content may be in order.

 

You don't need premium gas.  Depending on how long it's been sitting, you may want to drain the old gas and put in fresh gas.

[75sv1]

I use Shell Rotella T6 5W-40 Full Synthetic. I have used the T4 in 10W-30 and 15W-45. I use NAPA Gold or Platinum (with Synthetic oils). Any of the Diesel rated oils should work well. I run 87 octane in my Jeeps. I would have all the fluids changed. Tranmission oil, coolant, break fluid, differential oils. On transmission oil if an auto, use the Dex3Mercon. Or is ti Dex2Mercon? I would put some Sea Foam in the gas tank.

[cruiser54]

Engine Oil Viscosity.doc

[pizzaman09]

I'm a fan of Wix filters.  I think I'm currently running quaker state 10W-30.  Seems to have excellent oil pressure even at 254k miles.  I'll typically buy any brand oil as long as it's not Supertec.

I exclusively put 15W-40 Diesel oil in my 62 Austin Healey Sprite.  I hadn't even considered on putting something like that in such a new engine as our 4.0Ls.  I was always told the zinc was bad for the catalytic converter.

 

[Eagle]

10 hours ago, Stew0958 said:

I have read all of the posts, and am still confused.  My husband passed, leaving a 87 Jeep Comanche to my grandson...and no manual or instructions.  He will be getting it soon for his 16th birthday and I want to make sure it is ready to go.    I am not sure of the miles...it's parked in a storage facility.  Should I fuel up with High-test (premium gas)?  Can I get a consolidated bit of advice on the oil to use?  Please keep in mind that I just want the kid to have many more years to remember kicking around with papa in that jeep.  Thank you all so much for your expertise and advice.  Regards, Stew  

 

Welcome to the inner sanctum. When your grandson gets the truck, I hope he will join us, and learn to appreciate the Comanche as a unique and rare vehicle as well as a significant memento of his grandfather.

 

The factory recommendation was 10W30 or 10W40. I run Castrol Syntec 10W40 and change the oil and filter at 5,000 miles. My 1988 Cherokee has survived to 287,000 miles on that, so I see no reason to change. If you are in a VERY cold climate (such as northern New England or Montana/North Dakota), you might consider 5W30 or 5W40 for the winter months, just to get easier starting and faster oiling when cold.

 

Definitely drain or siphon the old gas out and fill it with fresh fuel. No need for high test -- standard grade is all that's required. The '87 has a knock sensor, so it will control the timing to avoid engine knock/ping.

[Stew0958]

Thank you all for the help.   I do appreciate the expertise and sharing.  I now have the tools to get the truck ready.  Also, I’ll be passing the torch of this site to him as soon as I can.  We live in the Western UP of MI, around 4 hrs N of Duluth (following Lk Superior).   Gets cold and lots of snow.  I suspect that the drive time will be reserved for summers.  Thanks again.  Regards, Stew

[Eagle]

UP? Do they use salt on the roads up there? If so, check ALL the brake lines (or have them checked by a mechanic, on a lift) very carefully. MJs do not like road salt, and the brake lines often fail as they age. A frequent point of failure is where the rear brake lines (there are two) pass over the gas tank.

 

If the brake lines look good -- have a shop or a trusted mechanic bleed the brakes to get the old fluid flushed out. Brake fluid is hygroscopic -- it attracts water vapor, which condenses in the brake lines and collects at low points, allowing the lines to rust from the inside out. I prefer to use silicone brake fluid. It's much more expensive than conventional brake fluid, but it's NOT hygroscopic, so it doesn't have the problem of getting moisture (and water) in the lines.