What do you oil experts think of Rotella T4 diesel oil in gas engines?  I do know it has pressure additives and zinc, but thats about all I know.

I ran 15-40 Shell Rotella years ago on my flat tappet FE drag car, but my understanding is that emission regulations required Shell to substantially reduce the ZDDP additive level, to me the later government standards a number of years ago. So I switched to Brad Penn/ Penngrade 1 about 15 years ago. Since that time, I have built 2 or 3 different 428 FEs, a 427 FE, and a small block Ford stroker for my drag cars, all with flat tappet cams, and the 428 CJ in my 59, a few years ago, never had a cam or lifter problem with the Brad Penn/ Penngrade oils.

I'm no expert, but I've seen a lot of information here, including some discussion of diesel oils in gasoline engines :
https://540ratblog.wordpress.com/

Get comfortable, there's a whole lotta reading at the link.

The long term effects of diesel oil on cast iron parts isn't good. Diesel engines have steel cranks, cams and lifters. There is a reason oil companies formulate different oils for different applications and don't have a one oil fits all.

Brad Penn/ PennGrade from Summit,Jegs or Internet.  Anything from a local parts store is probably low on zinc for our cars nowadays.  I don't really trust the off the shelf Rotella or Valvoline racing so I go the Penn grade in all my performance cars with flat tappets.  It's insurance.

Probably zero use for you North American guys, but maybe good info for some of the Euro guys, searching this topic. I have looked alot into oil specs and have found the German Liqui Moly Hi Tec Touring HD 20W 50. While the 'Hi Tec' term may cause concerns, it isn't at all what it's name suggests. Not a blended or synthetic oil, it is just conventional mineral based and it has over 1400ppm ZINC. A friend of mine who works at Mercedes trucks in Stuttgart told me about it. It's a good all year round oil for normal winter and summer temps ( 0 to 100 degrees F) and it was originally designed for old Mercedes and BMW engines from the 1960s to 1980s. For those familiar with old German cars. they have cam, chain, lifter and ring weakness which tend to wear extensively with age and milage ( The old saying goes that you will know a BMW by its blue smoke trails from miles ahead...hahaha). Now go figure Y block engines (delicate valve train lubrication). This oil is like it was made for Y blocks. it's only about 40 bucks a gln over here. Been using it for 10 years in ALL of my cars now. also good in Flatheads, banger and aircooled engines. JMHO.

my motor builder recommends Rotella for all his builds has ben for years he builds all kinds of motors and puts it in and Bracks in motors on dyno used it in my last wrecker had over 250000 on it was a 460 ford flat tappet motor i think its still going i sold it 3-4 years ago

Not sure about all the hype with respect to motor oils and for that matter hardened valve seats?  The 351C in my 36 was a junk yard engine out of a 72 Ranchero that I purchased in 74.  No idea of how many miles were on it, gave it a rattle can overhaul, put it in the chassis and have put 140K miles on it since 1980.  Just off the shelf oil, been running pump gas since then.  It has had no work done other than routine maintenance.  It seams to be OK as it starts up, runs well, yup, uses oil but don't smoke or drip.  Might be an unusual engine but that is the life story of it.

Here is my two bits worth as a former employee of Quaker State Oil. 

Check the API donut, if there is a SN designation, the S signifies it has met all the testing for Spark induced ignition. (Gasoline)

If it has CJ, the C signifies Compression induces ignition (Diesel).

If it has both it is good for gas and/or diesel, if only one then the other is out.  Diesel oils have a higher detergent package that suspends the dirt in the oil and will drain out with the oil.  Some Rotella is C only.

Thicker is not better, use a quality product and change it.  If the oil is dirty, it does not mean it needs changing, it indicates that it is doing its job and suspending the dirt and not letting it stick to everything inside like valve covers etc.

Terry
 

Quote from: Ford Blue blood on 2022-07-27 07:53Not sure about all the hype with respect to motor oils and for that matter hardened valve seats?  The 351C in my 36 was a junk yard engine out of a 72 Ranchero that I purchased in 74.  No idea of how many miles were on it, gave it a rattle can overhaul, put it in the chassis and have put 140K miles on it since 1980.  Just off the shelf oil, been running pump gas since then.  It has had no work done other than routine maintenance.  It seams to be OK as it starts up, runs well, yup, uses oil but don't smoke or drip.  Might be an unusual engine but that is the life story of it.

The thing here, is your engine was broken in almost 50 years ago, back when oils had more high pressure additives. Not to mention it sounds like a stock engine with stock, 48 year old valve springs. So between the cam and lifters having been run together for almost 1/2 a century, and a small, stock cam, with tired stock valve springs, it is hardly surprising that is is not fussy about oil. Now, put in a new, more aggressive camshaft, with new, stiffer valve springs, and new lifters, with your "off the shelf" oil and get back to me. As for valve seats, if you are just cruising, not likely an issue, but over the winter, I installed a new set of aluminum heads on the 428 Cobra Jet engine in my 59, because when I did a compression test, it showed a couple of cylinders had low compression. When I removed the stock, cast iron CJ heads, all the exhaust seats showed signs of the valves sinking. Towing, or hard driving tend to be harder on the non hardened valve seats than just driving easy.

I have recently been watching Vice Grip Garage on U Tube and have seen Derrick use Rotella in the cars he starts up that have been sitting for years.  Pretty much all of those cars are flat tappet engines. A lot of his content is silly but I do enjoy the troubleshooting aspect of it.
 I just changed my oil and for the first time used Rotella Oil in it due to the Zinc and comments made from the show and a few others. I knew the oil was for diesel but was not aware of the S and the C letters indicating Diesel and/or Gas compatible. I appreciate the discussion on this topic and hope to learn something.
I have used Castrol in the past and added some Zinc additive.

In general ...

ROTELLA was originally used by the hobby in gas engines when HI-ZINC was banned with the intro of catalytic converters.

It was a fast go to. EPA eased regulations a little later allowing HI-ZINC oils to be used in older applications. These were identified by their API RATING and PACKING DESCRIPTIONS.

Along with RACING OILS (such as VR-I) came a reduction in detergent/dispersal packages as they cause aeration/foam at high RPM. The use on a street engine is not recommended as an actual race engine is torn down on a scheduled basis and the oil dropped.

Modern oils have been modified as to preclude once needed large amounts of zinc. You would only actually need a HI-ZINC type oil if there is a large flat tappet cam used with high spring pressures or engine break-in and even then break-in springs would be used.

Current ROTELLA is a low zinc oil introduced for emission control diesel particulate traps. SHELL kept the old formula for industry use in older equipment but was only available in 5 GAL containers to keep it away from general public use.

As for exhaust valve seat recession in an aluminum head, they didn't have hardened valve seats?

Zinc  I guess the myth will never die 

I think the biggest factor is cost. Many seem to buy/use only by cost rather than formulation.