84’ 4x4 Rotella oil for non-diesel

[PsychoNaut04]

I’ll be doing more work on the truck this weekend. 
i see Rotella 15w-40 diesel is hugely recommended as the oil type for non-diesel engine. 
i pulled it up on autzone but it’s showing me different types. 
which one should i go for? 
 

https://www.autozone.com/searchresult?searchText=Rotella 15w-40

[ggzilla]

go for the full synthetic. I will still be full-strength after 3000 miles, while the conventional will start off good, but be worn out by then

[PsychoNaut04]

4 minutes ago, ggzilla said:

go for the full synthetic. I will still be full-strength after 3000 miles, while the conventional will start off good, but be worn out by then

Thank you boss 🙏 

[ggzilla]

I should amend that statement. After 3000 miles, the additives will have lost their strength in both. But the conventional loses a lot, while the synthetic is still working OK (but not like brand new). Anyways it is still recommended to change the oil at 3K in a carbureted vehicle and at 5K in an EFI engine.  The carby will end up diluting the fuel more than EFI will if both engines are in good working order

[datzenmike]

2 hours ago, ggzilla said:

go for the full synthetic. I will still be full-strength after 3000 miles, while the conventional will start off good, but be worn out by then

 

No it won't. You can go 5-6k on regular oils. Likely much further but the deciding factor is how dirty the oil gets. Synthetic is not immune from this either. Extended oil changes are ruining new car engines.

[powderfinger]

yeah, what Mike said. Regular engine oils will absolutely not be "worn out" by 3000 miles.

[datzenmike]

At 6k likely you have topped it up a couple of qts so that would have helped the additive package. 

 

When I attended Canby I would usually swing by Calgary on the way home and that would have been on the high side of 2k miles as I never take the most direct route. I would change my oil and filter every other year. All travelling miles so oil was brownish but never black.

[DwayneOxford]

When Walmart started carrying synthetic was when I began using it. I sent Blackstone a sample at 6K, said was good to go. Did same at 8, 10 & 12k. Additives and quality were down at 12K, so, I run 10K as long as it's still looking good.

[ggzilla]

yes, you can go 15,000 miles on conventional oil. But should you? The oil doesn't wears out, it is the additives that lose their effectiveness due to heat ,etc. All the reports I've seen say that synthetic stays more effective for longer than conventional. Extended 5K oil changes are still controversial for carbureted engines due to oil dilution. The additives help with this by binding with the fuel and keeping the oil working. Also standard oil filters are only good for 5K due to the rubber valve, after that the more expensive oil filters with the special valve is recommended

 

And now that full synthetic is only 10% more expensive than conventional, why buy the lesser type?

[datzenmike]

And what does synthetic have in it for the anti scuff ZDDP package? Or does it?

 

At 15K I should imagine that up to 5 new quarts have been added to keep it topped up. Just how much fuel can synthetic bind to in 15k of driving? I should also imagine the oil would be BLACK from extending the change interval by 5X. I know everyone says it doesn't cause leaks but I put a quart of synthetic in my 620 and right away a drip formed from a front crank seal leak that was never there before. After the next oil change it went away. Same with transmission and transfer case both leaked after switching to synthetic. I put new seals in, weren't cheap, but that fixed the problem. So fuck synthetic, I'm sticking with what works.... your results may vary. 

[ElliotV]

I've always been weary of running synthetic due to the horror stories of it causing issues with leaks on older engines that only ever saw conventional. One thing I have noticed between conventional oils and synthetics is that synthetics do in fact last longer, have more resistance to temperature, and stay cleaner for longer due to the amount of detergents. I noticed this in my f350 with 213k miles on a v10 on synthetic oil it never burned with a load on it no matter how fast I drove and the oil lasted a little over a year before it started burning(only 1500 miles since it didn't get driven much) just due to the fact that it breaks down after that long. When I did run conventional in it because I just needed cheap oil to change it got darker much faster than the synthetic did and it will burn if I run the engine hard enough with a load or just driving at faster speeds due to the low gearing the engine turns fast enough it would start burning off some oil. 

 

My 720 though that I have been driving for a year and a half using STP regular conventional oil and a zddp additive to get the zinc up it never burned unless I drove over 65mph for extended periods of time which wasn't often but it would make .25 of a quart disappear. When I switched to shell t4 which comes with enough zddp and installed the Weber kit I could drive at 70mph no problem with a much better running carb and it doesn't burn oil at all doing so even though both were conventional oils the shell is much higher quality and doesn't burn off as easy. 

[Stinky]

My in-laws had an 85 Camry....I couldn't believe it when I found out that he was changing the oil at 10K.  His response, "That is what the manual says."  We sold that car at 204K, still running like a top.

 

My '89 Camry....5K oil changes....it blew a head gasket at 250K

 

My 97 Camry....we bought it at 265K....it was still running fine when my daughter blew the trans at 304K....5K oil changes

 

Oil has come a long ways in the past 20-30 years.  But, we don't have leaded gas now and we have fuel infection.

[ggzilla]

I find it hard to believe a 1985 camry manual said 10K miles. Those older Toyotas were bullet proof though

1 hour ago, Stinky said:

My in-laws had an 85 Camry....I couldn't believe it when I found out that he was changing the oil at 10K.  His response, "That is what the manual says."

[ggzilla]

all modern oil has ZDDP additives. But is it reduced compared to the old days, if i recall because it increases friction, and the automakers value HP and fuel economy over longevity. Synthetic oil, which is still made from crude oil, uses ZDTP a different zinc-based additive that better matches the base oil

1 hour ago, datzenmike said:

And what does synthetic have in it for the anti scuff ZDDP package? Or does it?

 

At 15K...

no one recommends 15K oil changes except the automakers who are trying to convince you their cars are trouble-free ... they know how to sell cars

[toshts]

Here's some things to note based on what I've read on oil. As far as I remember this should be correct but I might have remembered something wrong. 

 

Modern oils favor antifriction over anti wear and this is shown in the requirements for oil certifications. Oils meant for cars have different standards then trucks and also diesels. Oils thicker than 10w-30 are allowed to have higher levels of zddp than those under with the assumption that they won't be in regular use cars. Ph level is huge in oils, as your mileage increases on an oil change your oil will change ph as it breaks down. It also loses viscosity as it breaks down, viscosity change happens faster in conventional than synthetics. Zddp increases acidity and detergents such as calcium and magnesium increase base. Apart from the damage to cats, another reason they can't have high levels of zddp in modern engines is too high levels of calcium can cause preignition in certain types of direct injection engines. Without proper detergents, high levels of zddp make the oil too acidic and it will cause excess wear on the engine. 

 

 

 

Here's an oil analysis breakdown of the rotella series from 2021, not sure if it's still the same but I believe this was after the most recent change in their additive packages. The synthetics have slightly less zddp than the conventional and synthetic blend with the t5 being the only one with noticeable moly and a better balance of calcium and magnesium. 

 

Things to note -

Rotella may have greater zddp than other oils but there are multiple types of zddp and I've heard that rotella doesn't contain the proper kind for flat tappet cams, not sure if that's actually the case but either way will be better than other oils without it.

Beware of additives. If you add straight zddp to your oil it will greatly increase the acidity and along with it decrease the lifespan of your oil. An example of this would be Rislones zddp additive which only has zddp and no detergents to balance the ph. If you start with a more basic oil it can work well. 

A zddp additive that has balanced ph out of the bottle is Lucas's break in zddp additive. It contains significantly more zddp than the rislone and also has calcium and magnesium at a ratio which balances the ph and won't ruin the longevity of the oil. 

Additive packages have to be specifically balanced to meet certifications so adding anything to an oil that has already been balanced will likely decrease the lifespan of the oil.

Castrol, valvoline and driven (probably more) make oils specifically formulated for flat tappet cams that have been tested and show significant decreases in wear compared to standard oils. There are conventionals, blends, and synthetics available.

 

[Thomas Perkins]

Castrol 10 W30 with Wix 51515 filter every 3000 miles.Works for me.

[PineClone]

So, what is the answer here? What i'm hearing above is Shell Rotella 15-40 synthetic?? This is the same oil I'm using in my 2016 Chevy Colorado 4 cylinder diesel (although it is 5w-40). My "new" 720 is getting an oil change tonight if I have the time.

 

From a previous thread here, I jotted down in my notes Shell Rotella T4 10W30 as the recommended choice (1985 Z24).

 

Edited April 11, 2025 by PineClone

[toshts]

2 minutes ago, PineClone said:

So, what is the answer here? What i'm hearing above is Shell Rotella 15-40 synthetic?? This is the same oil I'm using in my 2016 Chevy Colorado 4 cylinder diesel (although it is 5w-40). My "new" 720 is getting an oil change tonight if I have the time.

 

From a previous thread here, I jotted down in my notes Shell Rotella T4 10W30 as the recommended choice (1985 Z24).

 

Consensus seems to be conventional for the 720 and that synthetic is overkill and unnecessary. Rotella t4 is fantastic and 10w30 is what was recommended originally 

[datzenmike]

Newer cars use a different cam on valve or roller cams and the ZDDP in the old levels poisons the latest catalytic converters. They wouldn't make a 1,000 + ppm oil if it wore stuff out. Increased friction is if you mix your own additive and think if this amount is good twice the amount would be twice as good. You're driving an old Datsun that was designed to run on almost 60 year old ZDDP levels over 1,000 ppm. You don't give a shit if it had 0.0000000% more friction than the crap they sell today.

[toshts]

1 minute ago, datzenmike said:

Newer cars use a different cam on valve or roller cams and the ZDDP in the old levels poisons the latest catalytic converters. They wouldn't make a 1,000 + ppm oil if it wore stuff out. Increased friction is if you mix your own additive and think if this amount is good twice the amount would be twice as good. You're driving an old Datsun that was designed to run on almost 60 year old ZDDP levels over 1,000 ppm. You don't give a shit if it had 0.0000000% more friction than the crap they sell today.

Exactly ^^^

 

Anti friction and anti wear are very different. Some cases decreasing friction decreases wear, some increases wear. Same with increasing friction, sometimes decreases wear sometimes increases. Zddp is an antiwear additive that increases friction and is necessary in flat tappet cams as mike was saying. Zddp coats the surfaces of contacting metal with a coating that increases friction but that coating is what wears down off the metal instead of the metal itself, decreasing the wear. When two moving parts that contact don't rotate individually (such as a flat tappet cams) there is a lot more wear on them, having this coating to get worn down instead of the metal vastly increases the life of the parts.

[ggzilla]

4 hours ago, toshts said:

Zddp is an antiwear additive that increases friction and is necessary in flat tappet cams

Exactly. And why all modern oils have ZDDP in them. The only thing in question is how much ZDDP is enough? I'm guessing the original Datsun cams don't need a huge amount of ZDDP -- unlike certain Ford and Chevy cams that wear in less than 30K miles. Has anyone actually had their Datsun camshaft wear out with any modern oil changed regularly? If not, then what's the worry

 

And now that synthetic is practically the same price as conventional, it's no longer overkill. $18 for 5 qts synthetic blend, highly rated and tested

[Thomas Perkins]

This says for Diesel engines.My FSM and manual does not say to use diesel oil.Also had a Jasper Engine installed back in 2009 and it has had nothing but Castrol 10W30 in it .Head has 396,000 miles on it,engine has 110,000 miles on it.Had 720 for 31 years.Will a Nissan Dealer put Shell in your 720 in a oil change.Call them and see what they say.

Edited April 12, 2025 by Thomas Perkins

[ggzilla]

In other words, all new oil works fine. Just change it regularly

[datzenmike]

4 hours ago, ggzilla said:

Exactly. And why all modern oils have ZDDP in them. The only thing in question is how much ZDDP is enough? I'm guessing the original Datsun cams don't need a huge amount of ZDDP -- unlike certain Ford and Chevy cams that wear in less than 30K miles. Has anyone actually had their Datsun camshaft wear out with any modern oil changed regularly? If not, then what's the worry

 

And now that synthetic is practically the same price as conventional, it's no longer overkill. $18 for 5 qts synthetic blend, highly rated and tested

 

Wear is cumulative. By the time is apparent or measurable it might be too late. Just erring on the side of caution by keeping the ZDDP levels at what they were 50 years ago.

[ggzilla]

So err on the side of caution, even though it seems it works fine, don't use diesel oil in a gasoline engine?