Thread: from semi synthetic oil to synthetic

Why do you want to change? If the Castrol product is doing the job then my advice is to stick with it... The low temperature viscosity rating of Mobil one was a significant breakthrough for very cold climates of northern Europe and Nth America. That they could then develop molecules which expanded to provide the requisite viscosity as the temperature climbed was clever chemistry. I've no doubt that their stuff "clings" to metal parts like Castrol claims for Magnatec. In the day to day scheme of things, for the engine you have and the temperatures you're encountering, I doubt it warrants the premium you pay, a good percentage of which no doubt is the added cost of heavy advertising telling you how good it's supposed to be!!

EDIT: My former LS1 Commodore ran extremely well on Magnatec for 140k. On the very rare occasion I put it in for an oil change the smart arse service manager had it refilled with Mobil One (5W-30 as I recall) without telling me. It was totally leak free prior but started to weep oil through the rear main and burn it at the rate of 1L per thousand km! changing back to Magnatec 10W-40 stopped the weeping and the oil use was less than 100ml per thousand Km (except when it had an Italian tuneup)

Mobile One was used in the BMW factory engine bench tests for the BMW boxer engine development.
I was used with the engine running at 100% for considerable time to ascertain areas of engine wear.
The use of Mobile One have to be discontinue because were was not able to be seen after running for more time that the testing required.
They switched to other brands to be able to see the worn parts.
I know it by an engineer that worked there.
I just wonder if it will perform in an engine with 140000 km as it performed in the BMW engine which run at higher revolutions.

Which brew of M1 ?

They vary a bit in performance and it all depends into which engine it will be tipped.

eg. I wouldn't recommend 10w30 M1 in a TD5 or Rover V8, not enough anti-wear protection but would almost happily use their 0w-40 in the TD5. (Mobil Delvac 1 would be my preferred brew there)
M1 10w-30 would be a fine oil in a modern Chev/Holden V6/V8 but not my first choice.

They vary quite markedly in performance, the 0w-40 oil being aimed at the European engine manufacturers.

In oils the additive package reigns supreme, base oil is of a lesser importance these days.

Mobil use alkynated napthalenes where Castrol add a small amount of esters and it is the esters that give the oil that particular 'clingability' as esters are generally polar in nature.

I highly doubt you'll see any leaks, etc. from just changing oil as all modern oils are tested for general seal compatibility, seal swell/shrinkage, etc.

Is for a Peugeot 406 V6 2.9
I think that the castrol is 10-40

It depends on the manufacturing tolerances. I'm not bagging the product... it's a matter of why you're using it and whether it will provide the optimum response you're looking for.

for (an extreme) example: A close friend of mine had a C-182 aircraft with a Continental flat 6. It was used for light commercial work. He was advised to start using Mobil One ..which he did. The problem was that the stuff was too slippery and was not viscous enough for the 50 yr old engine design which did not have the close machine tolerances of modern roller rocker engines. 1,000 hrs later it cost him over $10k for engine repairs!

as far as I know Mobil 1 is jet turbine oil.

thats is what all Australian Army Aviation aircraft used when I was a framey.

thinking it may have been Mobil Jet 1......its been nearly 30 yrs....gasp.

Yeah Mobil do a jet 1, think it is jet II now.

Hoges, are you are saying your friend put automotive Mobil one in an aircraft engine? They do make a multigrade for piston aircraft engines though, but it's a mix of synthetic and mineral. Big difference with those engines to a car. They run at very limited RPM band compared to a car. Yes they use 'looser' fit than modern engines but they also use thick oil. Important point being is when they get damage they keep going. I've flown them with busted valves, badly worn cams, cylinders not getting fuel, even had a cylinder top bust off once! They keep running though. They get horrid fuel economy though