Conventional, Synthetic Blend, or Full Synthetic

[Manche757]

I think it would be enlightening to find out what CC members are putting in their Comanches.  Just a shared survey of sorts.  Not so much about the finer theories on motor oil, but more about what we are actually using.  Someone in Florida is likely using something different that someone in Minnesota.  So if you would, post like this:   10-30, conventional,  Virginia   If you use something different in the winter, note that.  For CA, indicate SoCal or NorCal.  

[Knucklehead97]

I run Havoline High Mileage Synthetic blend 10w30 in my north Alabama driven MJ. Does real good with it and the new Havoline 6-quart boxes are only like 14$... I run the same thing in my daily driven 97 Sentra with almost 200k on it. I change the oil every 3k in my MJ and every 8k in my Sentra (I drive it 58 miles one way to work)

[dvitha]

I have never ran conventional in any my cars ever. I have always used synthetic and since I opened my shop up in 1995 we only put synthetic in customer trucks, and in our company vehicles. You best bet is to run the temps rang you live in. 5w30 and 10w30 cover most of the US, but some real cold places way up north go with 0-30. Using 40 is good if you have a tired engine and things are not as close as they tolerances as oem. 40 and some times 50 are needed on very hot running engines that will make the viscosity thin by excess heat ( I mean really hot) Some sloppy engines like old vws required 20w50, but would say 10w50 in very cold areas.

 

I like to use synthetic because it is cleaner and does not tear up the gaskets as bad. If you have a vehicle that has leaks synthetic can make leaks worse. The Tractors we service also run synthetic. We at the shop get 5 quart mobile 1 for 10 dollars a jug, at Walmart I seen them between 18 and 25 dollars for 5 quarts. Still not bad price since the oil is good from 5k to 15k. We like to change oil on the old vehicles at 6k, and go by the factory mileage on the newer which is normally 7500 on lots of vehicles these days.

 

Like quality parts, put quality fluids in your vehicles they will last longer. If you put cheap parts you maintenance sooner then with better quality.

[gogmorgo]

I use synthetic if it's on sale. Generally I go for 5w40, generally the diesel variants, but in summer if I'm putting a ton of miles on in a hurry I'll go 15w40 conventional cause it's cheaper. 

At work we put 5w40 synthetic diesel oil in everything, and I mean everything, from generators and lawn mowers to Subarus to Powerchokes to the big Cumminses in our Western Star highway plows, mostly I think cause that's what comes out of the tap in the ceiling, and it's just easier that way. Hasn't seemed to cause any problems yet. Some of our trucks rack up the miles, too. We finally surplussed an '06 3/4-ton Chevy this winter that had 455,000km/280,000miles. The truck that did the road condition monitoring is a 2015 Chevy half with 340,000km/210,000miles. Yeah, over 200,000 miles in three years, it was on the road pretty well all day every day. The truck that replaced it this spring already has 30,000 miles on it. 

 

Newer engines are calling for much lighter oils, in the 0W20 range, which I'm pretty sure is just for improved fuel economy. They get 5w40 as well, and it hasn't seemed to cause any problem there either. 

 

I've pretty well come to the conclusion that keeping on top of your oil change intervals is probably going to serve you better than using the best oil but getting sloppy about changing. New, fresh oil is going to do you much better than old worn out, dirty oil, no matter what the new stuff is, or what the old stuff used to be. 

[Eagle]

Full synthetic, Castrol SynTec. I ran 5W50 when it was available, but nobody carries that grade any more so I typically run 5W30 in winter and 10W40 in summer.

 

Connecticut.

 

Oil change interval 5,000 miles.

[SVPete]

Conventional 10W30. Live in Southern, Southern Arizona. Change oil and filter about every 4,000 miles.

[Pete M]

years ago I ran full syn until it became obvious I needed to change the oil every 2k and then it got cheap-as-it-gets oil.    and I can feel the difference when the new oil goes in, even after just 2k .

 

every other ride in my family gets full syn.    

[DirtyComanche]

Basic rule of thumb is (for a 4.oh):

-Name brand synthetic, although I often use Lucas since I get a hell of a deal on it (I don't consider Lucas a name brand), but no Walmart oil or whatever.  Pennzoil, Mobil 1, and Valvoline are my normal name brands.

-10w30 year round since I don't like doing maintenance based on a calendar schedule

-Always gasoline oil only, no additives beyond what's already in it

-Change it at about 5000km because I don't drive that much, but a lot of it is off road or other 'severe' conditions, and that's a nice even number to remember.  I debated going to filter changes and top ups at every second interval, but I do like to look at the oil as it comes out.

-Use a good filter.  Currently I've got a bunch of AC Delco Pro ones.

 

FWIW I've never blown up a 4L.  I've tried every gimmick, thicker oil, thinner oil, cheapest oil possible, diesel oil, camguard, ATF, run Fram filters, refused to run Fram filters, swamped it, not change the oil for 4 years, ran it out of oil, ran it with too much oil, overheat it until you're really afraid the head gasket will let go, run a broken tstat so it never heats up, and everything else you either should be or shouldn't be doing.  I honestly think it doesn't matters that much on a 4L that's already well enjoyed, pretty much as long as you stay within about 3 lightyears of what AMC recommended it's going to be okay.

[Dzimm]

I run valvoline high mileage 10w30 synthetic blend with Bosch oil filters on all my XJs/MJs.  Oil comes out more dark brown than black after about 4k miles. 

[75sv1]

On my RENIX, I used to run 15W40 T4 Rotella.  I have run 10W-30, 15W-40 Rotella in both of my XJs. I am presently running Rotella T6. Mine dose leak a bit though. I second the if it leaks, don't use synthetics. Conventionals have come a long way, though. I do run synthetics in my other vehicles, if they do not leak. I started with Castrol Syntech. It worked well. There was no sludge, basically looked new, when I had the valve cover off at 124K. I used Shaffer for a change, then Pennzoil Platium to 214K. That one did not use oil. I did use Mobil 1 ?W-50. It was to heavy of an oil for that engine.

          If using Synthetics, I'd keep the same grade year round. Although I am not in Alaska or such. I run at least 7K miles on synthetics. I have gone 12K on some changes. I use Wix, NAPA oil filters. They do make a filter for synthetics.  I also run a larger filter. I have an '81 MB 240D. I do change to a thinner grade of oil about November 10W-30 Rotella. This is a starting issue. According to the manual, this is fine under 70F. Different vehicle though.  I'm in IN.

[eaglescout526]

I run the valvoline 10w30 full synth as well all year round here in Phoenix. Usually change my oil about every six months with a MoPar oil filter. Haven’t had any issues using said oil. 

[HOrnbrod]

Chevron Delo 400LE 15w-40 diesel motor oil synthetic year round. I run this oil because of the high zinc content and high zinc is best for our 4.0 flat tappet cams.

[AZJeff]

21 hours ago, SVPete said:

Conventional 10W30. Live in Southern, Southern Arizona. Change oil and filter about every 4,000 miles.

Synthetic 10W30.  Change oil and filter every 4500 miles.  I live in an even HOTTER part of AZ, near Phoenix.  The synthetics tolerate heat MUCH better than conventional oils, which is the main reason I use them.

[SVPete]

2 hours ago, AZJeff said:

Synthetic 10W30.  Change oil and filter every 4500 miles.  I live in an even HOTTER part of AZ, near Phoenix.  The synthetics tolerate heat MUCH better than conventional oils, which is the main reason I use them.

 

Yes...Phoenix and Tucson are much hotter than down near the border.

[WahooSteeler]

18 hours ago, HOrnbrod said:

Chevron Delo 400LE 15w-40 diesel motor oil synthetic year round. I run this oil because of the high zinc content and high zinc is best for our 4.0 flat tappet cams.

Since I can't run 15w with our winters in central VA, I usually run a 5w-30 synthetic and add Rislone additive with ZDDP. That said, I plan on starting to run Rotella T6 5w-40 synthetic based on a really in-depth study of several different oils and the different levels of additives they have, pros and cons of each additive, and which one seemed to make the most sense for the 4.0L. The T6 variant has, IIRC, high levels of zinc also. I'm pretty sure it was a thread here on CC. 

 

For Amsoil fans I also came across a high zinc formula they make called Z-Rod in 10w-30 or 20w-50. $13/quart though! I guess if you do 2-3 regular changes per year and only one change with the Amsoil it comes out about the same.  

[HOrnbrod]

I think the Rotella T6 5w-40 synthetic is just as good as the Chevron Delo. I use the Chevron because Hesco recommended it for my stroker crate engine, and that's good enough for me. Been in my rig since 05; still running strong.

[Manche757]

I am surprised to learn some are switching back and forth from conventional to synthetic (or blend) and back freely. Are there no compatibility issues that gum up? I assume no cleaner is being used in between for fear of damaging seals on old engines?

 

I am also surprised at 50 weight oil being used in Canada, even if blended with lower viscosites.

 

No one commenting on conventional oils being paraffin or asphalt based?

 

When posting what you are using, it is meaningful if you give general location. If more of you post what you are using, there will be better information for us all.

[75sv1]

This might be the link referred to:

https://www.cherokeeforum.com/f2/rotella-worlds-first-ever-combined-hair-oil-foot-ointment-salad-dressing-188168/

 

       As stated before, I am running the T6. I have no doubt that Delo is just as good or even a bit better. I do not have heat issues in IN. As least to the extent that others do. You also might look at Bob Is The Oil Guy website for Group 1-2-3 and Synthetic groups. Basically, Conventional oils are Group 3s (III). They are highly modified. Some synthetics (Castrol) are a higher grade of this. I have switched back a time or two from Synthetics to conventional, with no apparent issues. I do not know if this is a carry over from the early synthetics. You could not mix with conventional nor switch back. This was the 70's to early 80's. I am surprised with the low oil change mileage  with synthetics. Still, I do not know the conditions being run. Also, with T6, Blackstone Labs posted results on three different engines. T6 was as good or better than all others. On the one engine though (Corvette) it was not listed.

      As has been pointed out, a high Zinc (ZZDP ??) content is desirable for flat tappet engines. I think 1100 ppm to 1300 ppm.

[WahooSteeler]

75sv1, the guy "salad" is where I saw it originally in another thread and I think he had posted a link to another webpage, as I recall reading the full original report. Might have been on www.bobistheoilguy.com. You can tell on the link you pasted above he is screenshotting the various pieces of info in that thread. Anyhoo, very interesting info for any gear-head. Particularly interesting that even though the Valvoline Premium Blue Extreme has the highest zinc level, it is not recommended for flat tappet engines for other reasons proving that it's not just about high zinc levels. Also that the Walmart MAG1 actually hits a lot of the marks as a conventional oil and I'm sure has a great price. 

 

I don't know this "salad" guy's background or qualifications, and I think the info he is providing is clearly from another source's oil analysis data. But, seems like a useful chart for everyone depending on where you live and the climates where you run your 4.0L. This "salad" guy is in Ontario Canada, and T6 may be the best for his motor but not necessarily the best for our members in AZ, TX, AL, VA, CT or wherever! I like 757Manche's idea to have this thread so we can all be better informed as to what can maximize the life of our 30yr old 100-300k+ engines. 

[75sv1]

I pulled the link from MeanLemon's site.  The main reason Zinc is being phase out is the new emissions controls, or cats. It clogs them up. Not much of a problem on older vehicles. A bit harder to figure out how the new additives do in our engines.

[Manche757]

What good things was zinc thought to do? Metalurgical reaction of some sort?

[Manche757]

On 9/10/2018 at 9:54 PM, Pete M said:

years ago I ran full syn until it became obvious I needed to change the oil every 2k and then j got cheap-as-it-gets oil.    and I can feel the difference when the new oil goes in, even after just 2k .

 

every other ride in my family gets full syn.   

What can you tell at 2000 miles?

[Pete M]

by 2k the horsepower has started to drop off.  an oil change brings them back.    the oil that comes out is black.  like, diesel levels of black.   I know it's tired... and I have an newer block to replace it... but I'm kinda curious how long it'll go. 

[dvitha]

I have one 4.0 that has nearly 700k on it. never rebuilt and still pulls hard and get good mpg. so it all depends.

 

[DirtyComanche]

4 hours ago, Manche757 said:

What good things was zinc thought to do? Metalurgical reaction of some sort?

 

When hot enough it leaves a deposit on friction surfaces that acts as a sacrificial layer.  Basically as the part wears it indiscriminately sticks zinc onto it to build it back up.

 

IMHO, the issue of the lack of zinc in modern oils is massively overstated.  Zinc was there because the oil sucked, the film strength wasn't high enough to prevent the cam from actually contacting the lifters, so something had to be done to prevent it from wearing the cam out.  Modern gasoline oils, especially good synthetics, have upwards of several times the film strength of older oils, and you're not going to see anywhere near the number of contact events as with an older oil.  Diesel oils, due to their extreme levels of detergents, will always have a much lower film strength than a comparable gasoline oil, thus they still need the zinc to not ruin cams as they're just not that good of an oil.

 

Also, indiscriminately adding zinc to the oil, by using an additive like Camguard, can actually cause you far more problems than it will solve.  Zinc actually becomes corrosive in high enough concentrations, and instead of coating the contact parts will attack the metal of them (it's actually essentially attacking it when it coats them to begin with, but it's not doing it that much so the whole thing is more or less in balance).

 

I honestly believe the whole "There's no zinc in the oil and the world is ending" thing basically is the result of internet myth perpetuated by anyone that has any sort of a failure blaming it on the oil not having enough zinc.  Yet there's plenty of beater XJs out there that have whatever the cheapest oil possible is put in them, by the worst oil change places in the world, on a  "when I've got $30 to spare, don't need a pack of smokes or beer, and actually remember" maintenance schedule, and they're trucking along just fine with less failures than any comparable vehicle.

 

Oh yeah, and throwing thick oil in it so you have "lots of pressure on the gauge" has nothing to do with how much pressure there is at the bearings, or if the oil will actually maintain it's film strength.  GM figured it out a long time ago, it's more about flow than pressure.  Low oil pressure is a symptom of wide clearances on parts or other wear issues, and adding thicker oil until it's back into spec doesn't do anything to fix the actual issue and is possibly even worse for the engine as the bearing surfaces need a lot of fresh oil on them to remain cool.