Hey, we haven't had a good oil war in a while...

[Christo]

I've been using Rotella T4 since I got my coach. Barry Owen recommended the same when he rebuilt my engine last year. Flat tappet cams, ZDDP and all that. But here's a video that does an awfully good job discussing the science of why this might not be such a great idea:

What say you, members of the TZE fellowship?

 

[werewilfs]

Ugh. Don't make me have to change.

 

[Christo]

I'm sorry. We want the best for our babies though, no?

 

[Tom Katzenberger]

Hey I just watched his video on zinc two minutes ago.

 

[Christo]

Hey I just watched his video on zinc two minutes ago.

Yeah, I saw the Facebook post on Zinc and went down the rabbit hole. The guy has the credentials... What I've learned so far is that he strongly recommends synthetic, and that the NAPA brand full synthetic actually tested better than Royal Purple or Amsoil. I'm going to continue running through the videos and see what else I can learn. Gotta decide what the best alternative would be to good old Rotella T4. The good news is that I have a newly rebuilt 455 and I get my oil tested at Blackstone Labs, so I'll be able to publish some data for all to see!

 

[werewilfs]

I'm sorry. We want the best for our babies though, no?

You're not wrong. It's mostly been my blissful ignorance.

 

[Keith V]

Lake Speed ( is that his real name??!! ) really has some good info out there. Well documented and tested.
He really likes a 40-50w synth automotive grade oil. Thats what I'll be using the next change!
It sound like while some synth oils are 'better' the difference is so slight it doesn't really matter

 

[Tom Katzenberger]

I think Larry W. had a previous thread addressing all these issues. He ended up with Quaker State. I used Quaker State for several oil changes, went back to Rotella because I buy it in 55 gal drums. I just replaced my old engine and used Mobile 1, 10w-30 in this last oil change. Every couple of years the formulations change and a new winner rises. The oils just keep getting better. Even for the flat tappets. IMO.

Take care all, I will be watching.
Tom K.

 

[tmsnyder]

Amsoil makes a high zinc full synthetic oil for flat tappets

 

[werewilfs]

Amsoil makes a high zinc full synthetic oil for flat tappets

Which one is that?

 

[radcaddy]

You guys (and that video) are confusing me... I am sticking with Barry and ChatGPT:

Shell Rotella T4 15W-40 is actually a popular and well-regarded choice for the Oldsmobile 455 Rocket engine, particularly among vintage car and muscle car enthusiasts. Here’s why it works well:

Why Shell Rotella T4 Is a Good Fit for the 455:

1. High Zinc and Phosphorus (ZDDP) Content:
   • The flat-tappet camshaft in the Olds 455 needs the anti-wear protection that ZDDP offers.
   • Rotella T4 has higher ZDDP levels than modern passenger car oils, even though it's marketed for diesel engines.
2. Robust Detergents:
   • Helps keep old engines clean, especially those with looser tolerances and possible sludge.
3. 15W-40 Viscosity:
   • Ideal for older big blocks that may have some wear, especially in warmer climates.
   • Provides stable oil pressure at hot idle and protects during startup.
4. Readily Available and Inexpensive:
   • Easy to find at most auto parts stores, Walmart, and farm supply retailers.

Things to Keep in Mind:

• ZDDP Levels Have Decreased Slightly in newer Rotella T4 formulas (post-2017 API CK-4), but it still offers more protection than standard passenger car oils.
• If you're doing aggressive driving or high-RPM use, you might add a ZDDP booster or step up to something like Rotella T6 or a racing-specific oil (e.g., Valvoline VR1, Brad Penn, or Amsoil Z-Rod).
• Not always recommended for catalytic converter-equipped vehicles due to ZDDP content—but your 455 doesn’t have that concern.

Recommendation:

Yes — Rotella T4 15W-40 is a solid choice for your Olds 455, especially if:

• You're in a warmer climate,
• You want strong high-pressure protection,
• And you're doing regular oil changes (every ~3,000 miles or annually).

 

[RF_Burns]

Which one is that?

Amsoil Z-rod is designed for older engines with flat tappets. Comes in several viscosities.

https://www.amsoil.com/p/amsoil-z-rod-10w-30-100-synthetic-motor-oil-zrt/

 

[Keith V]

One of the things the Oil Geek stresses is that too much zinc actually increases friction and wear.
More is not always better.
Also Diesel oil has a lot of detergents which isn't that great for gas engines

 

[LarryW]

I think it is important to note, just because in the old days ZDDP was needed in oils to assist wear characteristics, doesn’t mean that it is needed in todays oils. Oils have improved immensely over the years. Todays knowledge of chemistry and engineering have created oil blends that give us oils that far exceed the wear characteristics of yesterday’s blends. Todays blends have chemical replacement elements that duplicate the elements of ZDDP, so there may be only traces or no ZDDP in the oil, yet have extremely high wear characteristics. These oils have been formulated to assist todays engines in meeting EPA standards. Since most of us are not experts in the wear characteristics of oil, we act on what we know from our past knowledge and experiences. The past is behind us and while relevant, we need to look at present engineering going into the future. I’ve done as much as my pea brain will tolerate in researching the best oil for my Cad 500. So far the best I have found is a blog by a guy that calls himself 540Rat. He has taken the time using engineering techniques to test over 300 different oil blends, and ranked them by their ability to resist wear.

https://540ratblog.wordpress.com/2013/06/20/motor-oil-wear-test-ranking/

This is a tough read filled with testing, engineering data, a lot of self praise, bluster, and a lot of information that we don’t need, but is the best I have found to help me in my decisions relative to the oils that I am using in my vehicles. While it would be best to read most of the beginning info, for the meat of the blog, grab the scroll button and scroll about 1/10 of the way down to “WEAR PROTECTION RANKING LIST”. This lists oil in their ability to resist wear by measuring in psi their ability to keep metals from making contact. It should be noted that while he has tested an number of them ranked very high on this list that have an aftermarket oil additive, he does NOT endorse the use of oil additives claiming that you really don’t know what you are doing to the carefully engineered chemical blend when you pour in these additives. So he claims it is best to choose an oil that ranks high on the list straight out of the bottle. He also claims as a result of his testing that the amount of ZDDP in the oils has nothing to do with the oils ability to resist wear....something that is opposite of what we have been led to believe by the oil companies for the last several decades.

* Over 150,000 psi = SPECTACULAR wear protection

* 135,000 psi to 150,000 psi = AMAZING wear protection

* 120,000 psi to 135,000 psi = FANTASTIC wear protection

* 105,000 to 120,000 psi = INCREDIBLE wear protection

* 90,000 to 105,000 psi = OUTSTANDING wear protection

* 75,000 to 90,000 psi = GOOD wear protection

* 60,000 to 75,000 psi = MODERATE wear protection

* 50,000 to 60,000 psi = UNDESIRABLE LOW wear protection

* Below 50,000 psi = CAUTION – EXTREMELY LOW wear protection

The HIGHER the psi value, the BETTER the Wear Protection.

I personally use #11 5W30 Quaker State Ultimate Durability, dexos 1 – Gen 2, API SN “Plus”, synthetic (green bottle) = 133,125 psi, in my automobiles and in my motorhome. It can be found at any Walmart for around $23/5qt. Yes, the Amsoil products right out of the bottle have tested higher on this list, but the cost/benefit ain’t worth it for me. Two years ago I switched from Mobil 1 European blend 0W40 (#18) to the Quaker State 5W30 synthetic. Oil pressure I my Cad 500 is 43# steady at highway speeds, and the lowest I've seen it is 25# at idle after a hot run with pressure quickly upping to 35# after a few cool down minutes. I do regular oil analysis at Blackstone Labs and watched metal counts drop noticeably after the switch to the Quaker State to below national averages.

If you want to see where the oil you have been using ranks, do a command F or Control F, type in the brand of oil, and hit CR to advance through the article until you find it. Use the word Shell for the Rotella oils) Some of the oils that have been the staple of the GMC community for years are surprisingly low, down around the 70,000psi on the wear protection list.

Sooooo….judge for yourself. Choose wisely by making informed choices.
JMHO

 

[Christo]

You guys (and that video) are confusing me... I am sticking with Barry and ChatGPT:

Shell Rotella T4 15W-40 is actually a popular and well-regarded choice for the Oldsmobile 455 Rocket engine, particularly among vintage car and muscle car enthusiasts. Here’s why it works well:

Why Shell Rotella T4 Is a Good Fit for the 455:

1. High Zinc and Phosphorus (ZDDP) Content:
   • The flat-tappet camshaft in the Olds 455 needs the anti-wear protection that ZDDP offers.
   • Rotella T4 has higher ZDDP levels than modern passenger car oils, even though it's marketed for diesel engines.
2. Robust Detergents:
   • Helps keep old engines clean, especially those with looser tolerances and possible sludge.
3. 15W-40 Viscosity:
   • Ideal for older big blocks that may have some wear, especially in warmer climates.
   • Provides stable oil pressure at hot idle and protects during startup.
4. Readily Available and Inexpensive:
   • Easy to find at most auto parts stores, Walmart, and farm supply retailers.

Things to Keep in Mind:

• ZDDP Levels Have Decreased Slightly in newer Rotella T4 formulas (post-2017 API CK-4), but it still offers more protection than standard passenger car oils.
• If you're doing aggressive driving or high-RPM use, you might add a ZDDP booster or step up to something like Rotella T6 or a racing-specific oil (e.g., Valvoline VR1, Brad Penn, or Amsoil Z-Rod).
• Not always recommended for catalytic converter-equipped vehicles due to ZDDP content—but your 455 doesn’t have that concern.

Recommendation:

Yes — Rotella T4 15W-40 is a solid choice for your Olds 455, especially if:

• You're in a warmer climate,
• You want strong high-pressure protection,
• And you're doing regular oil changes (every ~3,000 miles or annually).

AI parrots the data it's trained on which, in this case, includes a lot of potentially incorrect popular sentiment. It's not a good way to refute lab testing, it just sounds good.

 

[LarryW]

Some additional notes here....

The one thing I have learned is that with today’s oils, thicker is not better. As 540rat has said, it is best to use as thin of an oil as possible, high on the “Wear Protection”, that give you acceptable hot oil pressure. For years, the standard has been, 10psi per 1000rpm. Meaning 2Krpm would be 20lbs, and 3Krpm would mean 35lbs. Personally I like to see more than that. So, the thinner it is, the more oil you have going to bearings, reducing wear. The thinner it is the more oil is carrying heat away from moving parts. The thinner it is at cold temps, the quicker oil gets to the bearing surfaces reducing wear. The thinner it is at cold temps, the more oil you have actually going to those cold surfaces quicker, reducing wear. I used to use the 0W40 mainly because the “0” flows for my Wisconsin cold winter starts, (winter temp often at -15*) while giving me the “40W” for acceptable oil pressure on hot running. On cold starts, I have oil pressure immediately with the "0W", and 45-48lbs hot running down the road, and 30lbs and a hot idle. I think it is Matt C. that once said, the only down side is the “0” also has a run-off factor when sitting for long periods, meaning because of the low viscosity, it runs off easier than the 5w to 15w weights when sitting for long periods. If my coach has been sitting for more than a couple of months, I get by that by pulling the ignition wire and turning the engine over until I see the needle move on the oil pressure gauge….then hook up the wire and start. A minor inconvenience but IMO worth the effort.

As a side note, one of the other things I noted is that many of the lowest rated oils in terms of wear, were the “Break-in” oils. Most of them rated in the Moderate to Undesirable Low category. Supposedly formulated to allow wear to take place for parts to wear-in to each other. My question is…why would you want wear to take place in a new engine? The cylinder walls…yes…but bearings? And, how does an oil decide what to wear-in….it can’t, so everything wears a little putting a lot of debris into the oil right away. If you look through a microscope at a final hone on a cylinder wall, you will see peaks and valleys. In the break-in process, the rings knock off the peaks. There isn’t an oil out there that can prevent that. IMO, break-in takes place in the first one thousand miles in the first couple of oil changes. One at about 50 miles and the next at 1000 miles. This last engine I built, I broke-in with a 10w40 synthetic blend. Engine consumes about a quart in 2K miles, and some of that is leakage out the front main seal. Next engine I build will get broken-in with the oil I plan to use for the rest of it’s life…Quaker State 5W30 synthetic.

I think it was Matt that also said that it is hard to find a "bad" oil out there, so to my way of thinking, if you have engineering and scientific testing that shows certain oils are better than others in reducing wear, why not go with it.

Just my relatively informed, off the cuff, back yard mechanic, gut level, eyeball it up and guestimate, (based on some actual research) opinion...that's all...

 

[radcaddy]

AI parrots the data it's trained on which, in this case, includes a lot of potentially incorrect popular sentiment. It's not a good way to refute lab testing, it just sounds good.

No doubt, however, the point is that if the Rotella T4 has sufficient characteristics to run the 455 for a few thousand miles a year, regularly changed, then the arguments are pedantic and cumbersome. So, like you, it would seem that the experience of running the T4 over a number of years successfully should show its a safe option.

 

[Christo]

No doubt, however, the point is that if the Rotella T4 has sufficient characteristics to run the 455 for a few thousand miles a year, regularly changed, then the arguments are pedantic and cumbersome. So, like you, it would seem that the experience of running the T4 over a number of years successfully should show its a safe option.

I'm not suggesting Rotella is unsafe, just that it may be sub-optimal. With my new engine, if I have data that supports making a better choice -- like not using an oil formulated for diesel engines just 'cuz we've always done it that way, my inclination is to follow the data. If it has some positive impact on longevity or performance, terrific!

Yours in science,
Christo

 

[tmsnyder]

I'm not suggesting Rotella is unsafe, just that it may be sub-optimal. With my new engine, if I have data that supports making a better choice -- like not using an oil formulated for diesel engines just 'cuz we've always done it that way, my inclination is to follow the data. If it has some positive impact on longevity or performance, terrific!

Yours in science,
Christo

I'm not an oil expert, but I did stay at a Holiday Inn last night .

I think there's more to oil than slipperyness.

For instance, there are different additives in oil for gas engines than for diesels. Mostly dealing with contamination from the combustion byproducts. Different byproducts; different additives.

Amsoil seems to have the best of both worlds, very high slipperyness plus the full zinc level. Yes it's expensive ($15 per quart) but how many quarts a year do you need? 10? 20? That's only $150-300 a year for oil. Pretty inexpensive all things considered.

I'm pretty checked out of this oil war though, my freshly rebuilt engine is a full roller specifically to get away from this question all together LOL. I just run full synthetic, and based on Larry's post I'll be using Quaker State Full Synthetic

 

[radcaddy]

I'm not suggesting Rotella is unsafe, just that it may be sub-optimal. With my new engine, if I have data that supports making a better choice -- like not using an oil formulated for diesel engines just 'cuz we've always done it that way, my inclination is to follow the data. If it has some positive impact on longevity or performance, terrific!

Yours in science,
Christo

What the video did not address is the fact that our engines are normally-aspirated carburetorated engines that produce soot. Not the fuel injection engines he’s discussing. So the relative advantage of the T4 seems a better choice. Doesn’t that play into it?