Bet you most people would fail epicly

 

40-grade oils are NOT specified for my engine. The factory service manual clearly shows 5W-30 and 10W-30 for my Jeep. 40-grade is not on the chart at all.

In the Motor Oil University articles, the writer clearly shows the differences in viscosity between 20- and 30-grade oils at a running temperature of 212 degrees-Fahrenheit. It is not much. There is a few centistokes difference. This is so minimal that it makes very little difference in oil flow on the highway. There is slightly less resistance to flow with the 5W-20 oil, leading to better engine cooling, better engine oil flow, lower oil pressure, better cleaning of the engine (evidenced by the leaks now present under my vehicle due to removal of crud buildup by leaky seals and by the coloration of the oil at each oil change), and better fuel mileage. Both grades of oil lubricate the engine equally well, so there should be no difference in iron content of the UOAs between two grades of the same oil.

I drive over 800 miles in one round trip from Twin Falls to Moscow. I do this four times per year, totaling half of all my mileage. All of my other driving during the year is done on short highway drives and short trips across town where, the oil typically does not reach operating temperature. In the past three years that I have been using 5W-20 Mobil 1 motor oil, my engine has been experiencing better fuel mileage, better performance, and produces less noise from the valves and bottom-end steel.

I will be sending a sample of this batch of oil to Blackstone to get a UOA, then I will run roughly the same mileage interval on a batch of 5W-30 and get a UOA done. I doubt there will be any significant difference, but if there is I will let you know (I'm always interested in the scientific stuff being an engineer-in-study and love sharing my findings). This winter, I will probably use 0W-30 or 0W-20 oil, but probably the 20-grade since it is usually close to or below zero up there.

When it comes to motor oils, it becomes a matter of preference and individual testing to find the correct viscosity of motor oil that works best in your engine. My engine was subjected to hard use and negligent maintenance for 75,000 miles of its life and was starting to run worse when the Jeep was given to me. With my upkeep, maintenance, and choice of automotive products, it runs better than many Cherokees with half its mileage that I've drove. For the last 35,000 that I've ran it, it has had zero engine troubles, when a trusted mechanic said that he'd be surprised if it made it to 210,000 miles without blowing a valve or losing a bearing. I run it hard, fast, and don't always let it warm up before taking off. Either my maintenance is keeping it running, or the engine is indestructible.

 

These are Jeeps, not space shuttles. Don't over think what oil to use. Some people just go nutty over this stuff, and there is no need to.

 

Agree totally. More energy should be focused on using quality oil filters.

 

Been a year since I changed mine.. I think I used a purolator filter and rotella 30.

 

If people worried more about their XJ cooling system like they do about what oil to use, there would never be any overheating threads to clog the bandwidth.

 

True story, right there.

 

Hahaha freakin true lol

 

My radiator and water pump are 23 years old, the electric fan doesn't come on, and the fan clutch spins easily. Do you think if I switched to Royal Purple my Jeep would no longer overheat in traffic?

 

Exactly. Why fix a problem when you can just keep putting band aids on it?

 

You gotta add Lucas..

 

^^lmfao

 

Nah. Rotella and an oversized Mobil oil filter helps cool the engine down. And also do the lifted good mod too.

 

More like...

My FRAM filters keep collapsing and causing bad oil pressure. Instead of buying a WIX or Mopar, I drilled a hole in it.

My 10-year old engine oil is too thin and when the engine heats up I hear knocking. Should I add an aftermarket oil cooler to bring the temp down?

No oil is getting to the rockers so I plumbed a line from the filter to the valve cover. Now I have no oil pressure. WHAT IS WRONG

 

Plumbed a line from the filter to the valve cover... Lmao!

You can save the trouble of all that and just use the oil pressure switch port.