Engine oil

[PeterN]

Just spotted this on ebay https://www.ebay.co.uk/itm/MANNOL-Defen ... Sw7zlZkXDz

Cheaper than Trago Mills! CF rated OK for 406 2l Hdi, not recommended for the 2.2 as its not low ash but I'm sure it would be allright. This is for 20 litres, free carriage.

Peter

[piglet]

Blimey that is reasonably priced.
I'm a bit sceptical on this semi vs fully synth thing.
Is fully synth really best for boring road Diesels or is it fashion driven?

[Welly]

Fully Syn is fine if the engine has always ran on it but there's a school of thought that by adding fully syn to an engine used to semi-syn it may start to shift waxy oil deposits around the system.....something best avoided. I think semi-syn is perfect for the HDi as it's a very unstressed unit.

[Bailes1992]

Synthetic oils are better in every way compared to their mineral counterparts. They last longer and can handle temperature changes better, they are thinner in extreme cold, maintain their viscosity in extreme heat and also keep the engine internals much cleaner.

Semi-Synthetic oils are a complete con, they can be 1% synthetic and the rest a Group 2 mineral oil. Treat all Semi-Synthetic oils as mineral oils.

If I had any 406 I'd either run a *w40 mineral/semi-synth oil and change it every 3k-6k or run a *w40 Synthetic oil and reach for an extended oil change interval of 6k-12k miles or 1 year. I'd have one or two used oil analysis done to ensure the oil I'm using is holding up correctly.

Synthetic oils tend to clean much better than mineral oils. If you have been running mineral oils for a long period of time you are likely to have a build up of sludge or deposits around old seals, if the synthetic oil cleans this up then it may cause a weep or a leak.

If I had an older engine that the history was unknown or has been run on mineral oils for a period of time like my Defender currently I would run a heavy duty diesel engine oil (running Morris Lubricants HD4 15w40 in the Defender at the minute) with an additive like Forte Seal Conditioner. Heavy duty diesel engine oils contain extra detergents and soot dispersant additives which will help to break down any sludge, varnish and deposits. Meanwhile, the Forte Seal Conditioner will soften, swell and make the rubber seals elastic again. I'm hoping later this year to change to a Group 3 or Group 4 Synthetic 0w40 or 5w40 oil in the Defender. The Defender did have a weep from the crank seal, the Forte seal conditioner seems to have stopped it in it's tracks!

There's also nothing wrong with running a heavy duty diesel engine oil in any 406 engine. If you do some shopping around you may find some good deals to be had buying it in bulk.

When looking at viscosities, if you're buying a mineral or semi-synthetic oil it's likely you'll have to choose from a 10w40 or 15w40. The 'w' rating tells you what the lowest temperature the oil is good for and the '40' tells you at operating temperature the oil has a viscosity that of an SAE 40 oil. This 'spread' is called the viscosity index. Mineral oils have a poor viscosity index which means viscosity index improver additives have to be used. Therefore, a 10w40 will have more viscosity index improver than a 15w40, VII's have a habit of shearing making the oil thinner over time. A 15w40 mineral/semi-synthetic will be a more robust oil than a 10w40.

However, with synthetic oils the opposite is true. Synthetic oils have a very good viscosity index. If you were looking for a synthetic 40 weight oil you will be choosing from a 5w40 or 0w40 oil. A 0w40 will be made from better quality base stocks then a 5w40 oil.

[Bailes1992]

Also, just noticed the oil in question is an ACEA A3/B3 oil which has a limited total base number. TBN is the engine oils ability to counteract crank case acids.

Really, you need an ACEA A3/B4 oil for a 406.

Or, if looking at heavy duty diesel engine oils I'd be looking at an ACEA E6, E7, or E9.