MG Sports Cars

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Bottom line recommendations:

1. Remember that the correct viscosity is your primary consideration. Increasing it beyond what it should be will cause more wear and heat. Reducing it below what is needed will cause additional bearing wear. Read your manual and use the “preferred” viscosity or the lowest viscosity that covers your temperature range.

5. Shear strength of the base oil is more important than a few parts per million of ZDDP. Synthetics will give the best protection, with Group II oils next. Try not to fall for the group I oils. This is not always easy to identify.

6. If you want the maximum valve train protection, look for an oil that is certified CH-4/SL or CI-4/SL without CJ-4. If the CH-4 or CI-4 comes before the SL, that is fine. Oils that are only SL certified have less anti-wear additives.

7. You do not want the API starburst. That is what tells you that it meets all the reduced phosphorous levels for catalytic converters.

8. The SM oils are not the end of the world. They use ashless antioxidants and better base oils than a lot of other oils. Wholesale price of an SM is about 6% higher than an SL because of this difference. The no-ash antioxidants make up for the phosphorous reduction in oxidation and the blend of better base oils improve the hydrodynamic cushion, reducing the time the engine is in mixed or boundary lubrication. This “better base oil” comment is only valid on the non-synthetic oils. A good synthetic already had that advantage.

9. If you have been using a low quality oil and move up to a CH-4/SL or CI-4/SL with 3000 ppm to 3200 ppm of detergent, don’t be surprised if it smokes a little for the first 3000 miles or so. It will clean up some of the deposits in the ring grooves and pistons, improving the cooling and ring movement. Once that has burned up the smoking will stop.

14. Forget the myth that you can’t switch over to synthetics in an older engine. Any formulation on the market today is totally compatible, and the better formulations will not only give you better shear protection and cold weather protection, but will clean up the sludge around the seals, allowing them to be softened to their normal size by the oil.

15. Forget the myth that synthetics cause leaks. The formulations of decades ago were pure PAO (group IV) that had poor solvency and tended to shrink seals. All of today’s formulations have esters or other ingredients that make them totally compatible with the seals, and the better ones will actually reduce leaking after a couple thousand miles.

21. Never change oil when it is cold. The oil should be as hot as you want to risk your hand. Change it at the end of a decent drive, when it is hot, thin, and the contaminants are in suspension.

25. After rebuilding an engine, always return to the original viscosity recommended by the factory. If done right you will have the original clearances. The use of a high viscosity oil, especially during break-in, may cause engine seizure on startup.

26. Don’t believe the myth that you can break in a rebuilt engine with synthetic oils. The argument that new cars come with synthetics so you can break in a rebuilt engine is totally false. None of us has the same work conditions, torque wrench calibrations or parts that the factory has. Use high quality mineral oil until the consumption stops; then switch to synthetic if you want maximum protection. Note: The use of Chrome or Moly rings in your rebuild will extend the break-in period. Don’t switch over to synthetics until oil consumption has (basically) stopped.

34. Forget aftermarket additives: As demonstrated earlier in this paper, when you buy a good oil, it has the proper compromise between cleanliness and anti-wear. With the right test equipment and conditions you might find a combination of ingredients that might reduce wear, but it will be at the expense of sludge and carbon. It will do you little good to reduce wear and rebuild the engine because it is fouled with carbon or the oil stops circulating because of the sludge.
The exception to this rule is an occasional cleaning additive, for one cycle. I do not recommend the “maintenance dose” of one or two ounces of cleaning additive per oil change that some additive manufacturers recommend. They are displacing anti-wear additives on the surface area.
Additives that claim to stick to the metal areas and therefore continue lubricating when there is no oil probably end up burning onto the surfaces, resulting in polished cylinders and lack of seal and oil control, with excess carbon build-up. They do not tell you what happens to them in the combustion process; and the upper cylinder and rings are exposed to very high temperatures.
Good rings clean off the remaining lubricant from the cylinder walls to avoid its burning and filling the hashes of the walls or getting burned in the combustion chamber.

35. Don’t fall for the “Meets recommendations for 19xx and older cars.” That means it satisfied the minimum requirements of cars made in those days to get them through the 20,000 mile warrantee, or whatever it was. The next generation oils were developed because those oils did not do what the manufacturers needed them to do. The oils marketed that way are usually cheap base oils with minimum additive packages. They shear down under stress; they have high foaming and oxidation, high evaporation, high sludge formation, high carbon build up in piston grooves and heads.

37. CJ-4 Oils: The listing of oils as CJ-4/CI-4/CH-4 means they have the reduced additive levels for low sulfur diesel fuel. The makers are allowed to say they replace CI-4 in diesel engines in the United States where the sulfur level has been reduced to 15 ppm. That does not mean they can replace CI-4 oils in countries where the sulfur level remains high (15,000 ppm in Venezuela, 500 ppm in Canada for on road and no limit for off-road). It is my understanding that Europe is now at 10 ppm.
The question of why CJ-4 can replace CI-4 when the sulfur is below 15 ppm is frequently raised, and it is due to the reduced need to combat the formation of acids and the way the sulfur breaks down the additives in the oil. The development of the CJ-4 oils was not performance driven, but emissions driven. The CJ-4 oils protect the catalytic converters on the latest designs of diesel engines, but the high level of ZDDP in CI-4 oils can, over a period of 300,000 miles or so, damage the catalytic converter, especially if the engine is burning oil or either base oil or the additives used are the cheaper more volatile ones. CJ-4 oils also have to be changed more frequently. CJ-4 does not replace CI-4 in Boundary lubrication (see page 2). The base oils used are normally stronger and provide more Hydrodynamic lubrication than the cheaper base oils, but in flat tappet engines they lose when that oil film is scraped off. Most modern diesel engines have roller tappets to eliminate this problem. Will a CJ-4 oil ruin your Corvair or other flat tappet engine? No. But it will allow more wear of the drive train than a CI-4. And it will allow less wear than the oils produced in the 1960’s. What if there was no oil in the market without the CJ-4? If I was faced with that decision (no chance, since I can have the oil formulated as I want, and our current diesel standards are 2000 ppm of sulfur) I would increase the viscosity of the oil in my Corvair from 10W-30 to 5W-40 or 10W-40, and it would be synthetic to get the maximum HT/HS viscosity possible.