Oil recommendations and questions here - The Definitive S2 Oil thread

[newsh]

Last oil change on the S2 Avant at 140,000 miles, I put in Mobil Synt-S 5w-40. I'm burning a lot of this and you can see and smell it in the exhaust. I've been recommended to try a 20-50 mineral or semi synth racing oil to see if it burns less.

Do you have any thoughts or recommendations on this?

[M_GORDON]

Hello Oilman.
I have an ABY avant with ADU+ spec and some things like Supersprint DP without cats.
My car have around 200k kms (and more ) and with 140k we rebuilt the engine.

My mecha put on 10w40 semisinth standar oil and now I bought 8 litres of Mobil1 5w50.
It´s ok?


Thank U man.

[EspenW]

Good points about the 10w-60. Too thick for regular use, costing power and increasing wear.
I use the M1 5w-50. Folks should check the oil temperatures they run and not just choose the thickest available.
Trackdays and continuous autobahn use is a different story, but regular driving (with plenty of WOT bursts as well) won't put the oil temp much over 100C.

[oilman]

Last oil change on the S2 Avant at 140,000 miles, I put in Mobil Synt-S 5w-40. I'm burning a lot of this and you can see and smell it in the exhaust. I've been recommended to try a 20-50 mineral or semi synth racing oil to see if it burns less.

Do you have any thoughts or recommendations on this?

Mineral and semi-synthetic oils generally don't help when it comes to burning oil losses. As both mineral and semi-synthetics have a 100% mineral basestock, what happens is that there is a mix of molecular sizes in the oil and the smaller ones evaporate and burn. In a synthetic oil, the molecules are the same size and don't evaporate and burn as easily.

A better option is to go for a synthetic 10w-50 as you will get better cold start protection.

http://www.opieoils.co.uk/c-659-10w-50.aspx

Cheers

Tim

[oilman]

Hello Oilman.
I have an ABY avant with ADU+ spec and some things like Supersprint DP without cats.
My car have around 200k kms (and more ) and with 140k we rebuilt the engine.

My mecha put on 10w40 semisinth standar oil and now I bought 8 litres of Mobil1 5w50.
It´s ok?


Thank U man.

5w-50 oils are okay, but the problem with them is they break down to be 5w-40 or 10w-40 oils pretty quickly due to the amounts of additives needed to make a 5w-50. It should be fine (but you may use a lot of oil), just next time try to get a 10w-50

[newsh]

Mineral and semi-synthetic oils generally don't help when it comes to burning oil losses. As both mineral and semi-synthetics have a 100% mineral basestock, what happens is that there is a mix of molecular sizes in the oil and the smaller ones evaporate and burn. In a synthetic oil, the molecules are the same size and don't evaporate and burn as easily.

A better option is to go for a synthetic 10w-50 as you will get better cold start protection.

http://www.opieoils.co.uk/c-659-10w-50.aspx

Cheers

Tim

Thanks for the reply Tim.

[pasbogdan]

What about mobil 1 10 w 60?You say it is to thick when hot.But what about the gauge showinh 130 degree celsius?I had a 10 w 40 in it and when boosted up(130 dgrs)the hidraulic tapets started to make noise.With w60 this is not happening.

[M_GORDON]

5w-50 oils are okay, but the problem with them is they break down to be 5w-40 or 10w-40 oils pretty quickly due to the amounts of additives needed to make a 5w-50. It should be fine (but you may use a lot of oil), just next time try to get a 10w-50

Thank U very much!

[oilman]

What about mobil 1 10 w 60?You say it is to thick when hot.But what about the gauge showinh 130 degree celsius?I had a 10 w 40 in it and when boosted up(130 dgrs)the hidraulic tapets started to make noise.With w60 this is not happening.

130c is around the top limit for most 10w-40s, so rather than a 10w-40, I'd go for a 10w-50.

http://www.opieoils.co.uk/c-659-10w-50.aspx

Cheers

Tim

[pasbogdan]

thx.
Mobil 10w60 is very cheap for me due my business contract i have.
10W50 is not

[oilman]

Okay, but the cheapest option isn't always the best

[s2_wot]

Hello Tim, would you be able to enlighten us on any problems switching from mineral to semi synthetic to synthetic.
Current thread here

http://www.s2forum.com/forum/showthread.php?t=48402

[oilman]

Thanks for the heads up, have got involved.

Cheers

Guy

[mouse]

In a similar vein is there any truth in this thread about premature failure of cams and cam followers due to removal of zinc and Phosphorous additives from modern oils?

http://www.ozaudi.com/forums/showthread.php/30395-Modern-oils-lack-of-Protection-to-flat-tappet-cam-cars-like-the-1.8t

[oilman]

Here's some info from John Rowland, a highly respected oil chemist of Fuchs and Silkolene


Part 1.

Zinc dithiophosphates, more correctly known as zinc di-alkyl di-thiophosphates,(ZDDPs) are very beneficial anti-wear/antioxidant compounds that have been used in engine oils since the 1950s. There is not the slightest evidence that they combine with combustion by-products to form acidic compounds. In fact, they also act as corrosion inhibitors. ZDDPs are the only phosphorus-containing compounds used in engine oils. As the name suggests, they also contain alkyl (hydrocarbon) groups, sulphur (‘thio-‘) and zinc, needless to say. Under pressure, they decompose at metal surfaces to form iron phosphide and sulphide layers which prevent micro-welding at contact points. (A.k.a. ‘wear’!).

The only problem with ZDDPs used to be that they formed heavy combustion chamber/piston crown/spark plug deposits of zinc oxide and sulphate in engines that burned a lot of oil. (They are not used in 2-stroke oil.) In modern oil-miser 4-strokes this is not a problem, but even small amounts of relatively volatile phosphates that escape down the exhaust can, in the long term, deactivate the catalyst. So there is a trend towards minimising ZDDP content in the latest petrol engine lubricants.

Very fine graphite (colloidal graphite) as an oil additive was occasionally used in the 1930s. It is never used now, because it is not very effective as an anti-wear, and it can block oil filters and narrow oil passages.

One of the very few effective replacements for ZDDPs are the oil-soluble molybdenum dithiocarbamates. These are now used in some oils (such as Ford standard factory fill) along with ZDDP.

Acidic compounds arising from the combustion of high-sulphur fuels are very effectively neutralised by a completely different range of additive compounds called overbased calcium (or magnesium) sulphonates. These have also been in use since the 1950s. they are present in substantial quantities in all good quality modern motor oils.
So stop worrying! 50 years on, oils are still looking after engines, and making a pretty good job of it.



Part 2

This fuss over ‘zinc’ is similar to the ‘lead-free’ panic of the late 1990s. I attempted to calm everyone down regarding ‘lead’ with a series of ‘Bulletin of the Morgan 3-Wheeler Club’ articles (widely circulated!) which I hope had some effect. Anyway, I’ve had no trouble with lead-free in my (unmodified) engines, and neither has anybody else as far as I know; unfortunately far too many valuable engines were vandalised by the fitting of unnecessary valve seat inserts. I am now trying to do likewise and defuse the damp squib which is the ‘zinc’ controversy, hopefully before anybody starts vandalising again!

1) When you look at a technical spec of an oil, there are the contents (often in ppm) of various elements quoted, such as phosphorus, sulphur, calcium, zinc, magnesium etc. These are measured by flame or plasma spectrographs which break down the very large, complex organic molecules containing these elements, so that the emission or absorption spectra of the elements can be detected. (When I use the words ‘organic’ and ‘elements’ I am using them in the correct, chemical sense!) THE PURE ELEMENTS DO NOT EXIST IN THE ACTUAL OIL; it is the complex oil-soluble molecules which do the anti-wear, detergency, antioxidant activity etc.

2) In oil, zinc is a component of an anti-wear/antioxidant compound, ZDDP, zinc dialkyl di-thio phosphate. It works because of the phosphate component (containing phosphorus) and the ‘thio’ (sulphur) component. The zinc has no effect on the engine; it just holds the ZDDP molecule together! (Rather amusing really; everybody’s worrying about the inert bit!)

3) So……if anybody suggests boosting zinc with zinc pellets or whatever, this will be utterly ineffective, and the pellets/gadget/magic zincerator should be inserted in the most sensitive orifice of the vendor. (Remember the moronic Broquet tin pellets which ‘prevented’ valve seat trouble during the ‘lead-free’ panic?!) In fact, the zinc in ZDDP is a pain. When ZDDP burns (in engines that use oil, and they all do, to a greater or lesser extent) the ZDDP decomposes to leave white zinc oxide, a refractory ceramic-like deposit that acts as a ‘glow plug’ and initiates pre-ignition. So, very high zinc oils are NOT a good idea….USA web-sites please note.

4) ZDDP is effective and cheap. It is possible to make a zinc-free engine oil with excellent anti-wear /antioxidant performance….at a price. They already exist, for piston aero engines, where high oil consumption leads to pre-ignition thanks to zinc oxide deposits. I’d be only too happy to use such an oil in my ’34 990cc Matchless V-twin…….but I will not have to! There will be oils with more than adequate ZDDP contents around for the next 50 years at least.

Yours sincerely, John Rowland (R & D Dept.)


Hope that helps.

Cheers

Tim