Good Article on Diesel Oil

[WahooSteeler]

https://www.motortrend.com/how-to/diesel-oil-in-gasoline-engine/?wc_mid=4035:23746&wc_rid=4035:34950555&_wcsid=12CEADA9231090A9C865D3248B7199A9B4CE5016E642276B

 

[FrankTheDog]

I’ve almost always use Castrol 10/30 or 10/40 in my 4.0’s and 2.5’s. Never had to have an engine apart. Three with over 300k and one with over 450.

[DirtyComanche]

I skimmed the article, and I think they missed one point on the detergents that is a huge factor.  Detergents lower the shear strength of the oil (the amount of pressure it can take before being displaced in a bearing).  Diesel oils have much lower shear strengths because of this, which is part of why they add so much zinc back into them, but it's also why diesel engines are designed much differently in regards to oiling and bearing sizes.  Really good oils won't shear, so there is no wear as the bearing surfaces will never contact, so you don't need much/any zinc.  This includes wear at startup before the pump is supplying lubrication.

 

The entire "I put the diesel oil in my gas because it's gooder" trend was started on bad science, they just looked at the zinc numbers and assumed that was all that mattered.  At best you're putting an oil in that performs about as well as a cheap gasoline oil, but at a much higher price, at worst you're actually damaging things.

 

Good synthetic GASOLINE oils are the way to go in gas engines.  Beyond that it's keep the oil clean (not just free of soot, but of water or gasoline) and keep it cool.  Add Camguard or similar if you're that worried about the zinc.

[GrandBoost98]

I think the most important thing for these old motors is that it has some type of oil and it gets changed somewhat periodically lol While I mostly agree with the article, I don't put our old N/A inline motors in the same catagory as a new v6 or v8, especially boosted ones. These motors don't rev all that much higher than a diesel motor under most circumstances. I have 100s of thousands of miles clocked over several of my jeeps that have all used Rotella T5 diesel oil. My wifes 18' subi on the other hand, that gets full synthetic car oil 

[FrankTheDog]

I banged my 98 XJ 4.0 off the rev limiter constantly for the last 240k of it’s 453k miles. I think it still leaked more than it burned ever. It was quiet right up to the end when l shipped it to the knackers.
l drove all my 4.0’s the same way and never had a problem. Always used Castrol 10/30 mostly sometimes 10/40 if it was a hot summer. Either in the white, green or black syntec. Depending on how flush l was at the time. Always Castrol though. I’ve never lost an engine in 40 years. The chassis’s always wore out first and they almost always were high mileage used vehicles.

Keep oil and coolant in it and it’ll treat you well.

[WahooSteeler]

My takeaway was that Rotella is still a good oil for 4.0s as low revving motor and they do benefit from zinc. I think the article was just an expansion on the notion "one size (type) fits all" approach is NOT a good thing, i.e. that ANY diesel oil and/or high zinc oil is better for older engines, muscle cars etc. It basically reiterated that there are so many different oils because there are so many different applications, so do a little homework and find the right one for the best long term results. 

[gogmorgo]

¯\_(ツ)_/¯ We run a diesel oil in our entire work fleet whether they’re diesels or not. It’s got the API ratings for both. In 200 vehicles that get run up past 200,000 miles we’ve seen two engine failures. One was a 200,000 mile ‘93 chev 350 back in 2018 that we were already planning on selling off, fired up before lunch to melt the windows off and when we came out it had a puddle of oil under the rear main and was seized. The other one was a 2014 chev 4.3 with around 150,000 miles on it that was left idling pretty well 24/7 all winter and typically was also over double the recommended mileage when it was eventually brought in for oil changes. While I can’t say the oil didn’t contribute to either of these things, it’s also not likely the choice of oil was the thing at fault for either failure. 
 

Yeah, obviously you should pick oils rated for the application, but that’s not to say there aren’t one-size-fits-all solutions out there. 

[75sv1]

I still go back to a posting on BITOG. It was analysis of oil test from Blackstone.  They did three different engines or vehicles. Rotella T6 was studied in 2 of them. It was at the top, with Amsoil. The third, Chevy Corvette, it was not reported in. AMSOIL was at the top of the list.