I've been reccomended to use 15/40 part synthetic on the v12. Would full synthetic be ok? Thanks

 

I prefer thicker oils for jag engines, 5/50 or 10/60 full synth

 

Witham qualube 20w/50 Classic oil for me with a high zinc content. I’m lucky as Witham Oils are one of our suppliers at work.
Rob.
https://www.withamgroup.co.uk/qualub...-classic-shop/

 

Ah. and Oil Type thread! LET THE BATTLE BEGIN!

Chevron Delo® 400 SDE SAE 15W-40 it is marketed to highway semi trucks, you'd call them Lorries. Lots of advanced soot/sludge control and lubrication properties not found in oils 30 yrs ago.

 

Ha!

Castrol GTX 20W50 only.

 

Archoil Friction Modifier is my choice additive, measurably faster rev, lower engine temps...very comparable to LiquiMoly CeraTec, though I've recently started using Lube Control https://www.lubecontrol.com/

Their oil additive chemically converts carbon sludge to a graphene lubricant not sure HOW but I noticed sludge stains in the crank case (visible from opening filler cap) have diminished alot.

 

Yes, full synthetic is fine. The oil viscosity will vary depending on your typical ambient temperatures. Years ago our local car club had a Lubrication Engineer from the Esso Research Center give a presentation on which oil to use. His recommendation was use oil with the lowest first number possible, and the second number as whatever the manufacturer recommends. For example, if 20W50 was recommended, use either a 0W50 or 5W50 if available.

The reason is the first number describes the cold viscosity and you wan the oil as thin as possible so it is pumped up into the moving parts as fast as possible upon startup. 90% of an engines wear is on start up, so you want the oil get to the engine quickly. 20 is not a good choice in that regard. The second number is the viscosity when hot, and that is what matters when the engine is up to temperature.

Neither too thin or too thick is good here either, as the bearing clearances are designed for a particular leakage rate. If the oil is too thin it leaks out too fast and doesn't provide the film strength. Too thick and the flow rate into the bearing is restricted, and again you have inadequate lubrication. Think of trying to suck a very thick milkshake through a straw vs water. You can get a lot more water though the straw. You also get much higher shear rates in the oil film and that generates heat. I have seen extreme cases where the head generated by shear in the oil has melted the lead in the bearings causing crankshaft failure.

The case I saw was in an industrial engine that typically runs at 100% load. The customer was an oil company and they had a policy to only use their own products. However they didn't happen to make an engine oil that met the specifications set out by the engine maker. So they used the closest oil that they made and put the engine into service. It didn't make it to the first scheduled oil change interval before the crankshaft failed and blew a hold in the block, making a $1.5 million dollar engine a 30 ton piece of scrap metal. The big problem for them was the waiting time to get another engine then was over a year and half, so it was a very expensive mistake to not use the right oil.

 

Is that rated for gasoline engines? Some of the dual service oils used to be and are now diesel only. I used to use Shell T6, but they changed the formula and removed the gasoline rating.

 

Id be curious to know exactly what constitutes a gasoline rating, my experience with modern diesel tells me its much much more particular than a 70s v12, the requirements are high and tolerances are so tight, you need the extra wear and lubrication, soot control etc. This sort of item is on-highway big rig stuff on extended drain intervals.

I buy it from the semitruck dealerships which price it nearly at cost - cheeaaap - and it has exceptional features. My car sprays oil like a cat in heat so I can't justify the import 10w60 stuff.

 

Look on the container for the API service classification roundel, and you'll see the various ratings. If there are ones starting with S (SN, SM, etc) then it is rated for gasoline engines. If the ratings are only C (CF, CG-4 etc) that is for diesel engines.

 

Yes but I'd have to wonder why, diesel handles more heat and pressure why wouldn't a suitable oil exceed your average commuter sedan's requirements by a mile?

 

How often do you replace the additive Vancouver?

 

For LubeControl It says, if I recall, 1oz per quart at first then 1oz every 1500km to maintain additive for LubeControl, I really should of taken before and after readings with all the additives I use but overall LC has diminished visible sludge, and given me a 2mpg improvement via their fuel additive on highway. Archoil (USA) and LiquiMoly have different specs, but all relative don't want to over do it and waste material.

 

I'm not a Tribologist, but I understand that the additives are quite different between gasoline and diesel oils, as the contaminants from the byproducts of combustion are quite different between the different types of fuels.

In the example of failure I gave above, the engine was running on natural gas, and there are specific oils designed for natural gas engines. Instead, the engine owner used a gasoline rated oil and very soon had total engine failure. For those particular engines, they started life as diesels, and then there was a variant that was converted to run on natural gas. The crank and bottom end was the same as the diesel, and the diesel version put out about twice the power of the gas version, so it was a very strong crank. Still failed with the wrong oil, even though they used the specified viscosity, but for the wrong fuel rating. It's the additives in the oil that make all the difference.

 

At the risk of going down a rabbit hole I looked into it

Relevant commentary here on diesel oils, chevron exceeds spec for gas and modern diesel so I'm safe! This reminds me of the oil test guy on youtube who does wear testing on every brand of engine oil imaginable - you'd be suprised to learn that basic PetroCanada 20w50 synthetic ranks up there with racing grade oils for heat/wear resistance...must be all that delicious bitumen in there haha.

https://www.youtube.com/channel/UCLQ...IA?app=desktop