synthetic or semi synthetic oil

You will find that better wear characteristics are claimed by the oil companies.

As an example, Valvoline claims:

SynPower meets the demanding performance requirements for BMW, Corvette, Lexus, Mercedes-Benz, Porsche, Volkswagen, Volvo and other high-performance vehicles. SynPower is an advanced, fully synthetic motor oil formulated for extreme protection and superior performance. It helps extend engine life by reducing wear and oil breakdown.

Compared to conventional oils, SynPower: Provides excellent engine cleanliness through superior sludge and varnish protection Helps reduce engine wear at high temperatures with improved viscosity stability Provides outstanding high-temperature protection under severe driving conditions Provides superior cold-temperature protection through faster oil flow at start-up Helps improve and maintain fuel efficiency for the life of the oil (applies to 5W30 and 10W30 grades) SynPower is fully compatible with all conventional and leading synthetic motor oils

Christian.

It is an expensive oil for high performance vehicles with extended drain intervals.

SynPower is an advanced, fully synthetic motor oil formulated for

Over extended drain intervals and in very high performance engines driven hard. No advantage in the majority of 'normal' engines.

They all say that. Pure marketing.

No doubt it performs better at extremes never encountered in most engines

See above

Only if lower viscosity versions are used than mineral oils [0w/40 is an impossible viscosity for mineral] and in extremely low temperatures relitive to the viscosity.

Of course this also applies to the same viscosity of mineral oils.

So are all mineral oils.

It should be noted that heavy diesel truck engines overwhelmingly use mineral oils even for extended drain intervals of up to 60,000kms under extremely tough conditions. Normal engine life between overhauls can be around 500,000 MILES.

How much longer will the Rav4 engine last using synthetic rather than mineral oil? Since it is quite capable of lasting about 250,000 miles on conventional oil would you like to put a figure on it? As I understand it the present usage would indicate around a 100 year lifespan potential on mineral oil so how many more years would it last on synthetic? Please be as precise as possible.

Huw

All European vehicles are high performance by US standards. BMW, Volkswagen and Volvo are just run of the mill cars.

Yes there is. Find some evidence to the contrary.

Bollocks. Fully synthetic oils have much improved sludge resistance over mineral stocks. Find a contrary source and quote it, please.

Synthetic oils are able to maintain viscosity, being nice and thin when cold, whilst maintaining enough thickness when hot. That is a serious benefit unavailable to mineral stocks.

Indeed. You will find that most fully synthetic oils do just that. A significant advantage of synthetic oils is that the thin cold viscosity provides protection at startup, significantly improving engine life and wear for vehicles that are frequently cold started, such as those belonging to commuters.

I believe Mobil 1 did a test on a conventional engine. They ran it for

Due to the synthetic oil's ability to last extended periods without deterioration, I would say that it was a good choice, unlike a cheap mineral oil, which will rot away and cease providing protection, unless replaced on such a frequent basis that the cost advantage becomes seriously negative before you even consider the cost aspects of the unnecessary labour incurred in changing it.

Christian.

In news:43577cc3$0$26878$ snipped-for-privacy@reading.news.pipex.net, Christian McArdle decided to enlighten our sheltered souls with a rant as follows

Magnatec is bloody awful stuff.

Shell Helix + Semi synth is the mutts nuts.

The message from "Pete M" contains these words:

Are they still claiming it magnetically attracts itself to the metal?

Well, I tend to steer clear of semis anyway.

Christian.

Out of interest, in what way?

Chris

Yup - looked at a bottle at the weekend. Doesn't actually claim that it is actually magnetic (although casually reading the wording could project that image). What it actually says is along the lines of "the unique whojimmawhatsits in the oil are attracted to metal, providing protection from the moment the engine starts, whereas normal oils take time to warm up before providing protection."

Or something like that....

Castrol did this sort of thing in the '60s. ;-)

I'd have to ask which one. The formulation is constantly changing.

Snipped for the benefit of others.

I'm with Huw. For the OP's vehicle synth would be a waste. Horses for courses innit. If you put in what the maker specifies you will not go far wrong.

I was talking to a AA man recently, about the extended service intervals on modern cars/vans, he thought that the service intervals were getting too long now, with the intervals thought up for fleet buyers, who will be paying for 2 or 3 less services over the projected 4 year life of the typical fleet car, meaning a saving of ~£500 for each car. He said if you buy the car privately, you should service it/change the oil a least every year/10000 miles, as even the best oil starts to break down after a few months, and cannot really be trusted to last 2 yrs/30k miles. Alan.

No doubt you are aware that BMW run computer monitored flexible service intervals? My 3.0l diesel averages over 14000 miles between oil changes. Certain VW and GM/Vauxhall engines have the potential for 30,000 mile oil change intervals using appropriate oils. This marks them out from run-of-the-mill vehicles with normal service intervals of less than 12000 miles. These engines call for specialist synthetic oils and exploit the sterling properties of these oils. Normal engines cannot do this due to various design issues.

It is up to you to find evidence. I make absolutely no claim that a synthetic oil is better than a mineral in normal engines. I have asked you for impirical evidence for your claims but you have not supplied.

Is this relevant if normal service intervals are followed? Of course not. The performance standard met by an oil measures sludge resistance among many other qualities. API SL oil has a very high quality whether it is mineral or synthetic. A high end mineral will be better than a low end synthetic. For instance, many mineral oils will meet mb229.1 but some synthetics cannot. Some mineral oils will meet BMWLL01 [odd but true] while mobil 1 could not until recently except in one viscosity grade which had a superior performance formulation.

Oil viscosity index is measured by a standard set by the SAE. All modern multiviscosity oils have the property you describe and their performance in both hot and cold conditions is as described on the can irrespective of base stock and measured against the same standard. Transmission oils have a different viscosity standard, again set by the SAE but not comparable to engine oil viscosity.

I use a 10w/40 fully synthetic oil in some applications and the flow is no better than any mineral 10w/40 at any temperature above -15C. I also use a variety of synthetics from 0w/30 in engines and also mineral oils from 10w/30 to 15w/40 multifleet long drain types where appropriate. I have no worries about lubrication induced wear or cold start wear using any of them.

You are basically correct. The engine was run continuously at a constant light load for the duration of the test except for oil change stoppages. There was no control engine run on high specification mineral oil. If there had been, I would surmise that neither would have shown significant wear and any difference would be of academic interest.

Synthetic oil is not a magic bullet and will not cause condensation and acids to disappear. This is one reason why Toyota specifically warn that should synthetic oils be used in their vehicles, then the normal service intervals should still be strictly adhered to.

Now then, I asked how much longer will the Rav4 engine last using synthetic rather than mineral oil? Since it is quite capable of lasting about 250,000 miles on conventional oil would you like to put a figure on it? As I understand it the present usage would indicate around a 100 year lifespan potential on mineral oil so how many more years would it last on synthetic? Please be as precise as possible.

You missed answering those last three paragraphs last time, due to an oversight no doubt, so I'll give you the chance once again.

Huw

He's been reading too many American comics. BMW and Mercedes have proven these long service intervals over many years now with success. Also I have an acquaintance who has run an Audi Allroad diesel for just under 200,000 miles with services between 20,000 and 30,000 miles apart and the engine still ran sweet as a nut. It was only sold because the automatic transmission was starting to fail and would have cost about £4000 to replace.

Huw

This would suggest that modern car engines are wearing out earlier than previously. The reverse is the case. When 1000 mile oil changes were the norm you'd likely need a full engine overhaul at as low as 40,000 miles. Now very few engines require an overhaul in the life of the car through actual wear.

Always use what the manufacturer recommends. Halfrauds do a chart showing what oil's can be used. IE Using a fully synthetic oil in an old ford zetec engine would be a bad idea, as the manufacturer only specifies 5/30 semi, anything thicker can cause the sticky valve problem (although some new synthetic oils are 0/30, which might be ok)

And it is inaccurate in many cases. Just like their bulb charts really.

I don't think Ford specified what type of oil should be used for those engines. They did specify a Ford and API standard and the API viscosity though.

Huw

The message from alan@darkroom.+.com (A.Lee) contains these words:

If this is true - are shorter intervals specified in other parts of Europe where company cars are far less common? It seems odd to skew the whole system just for one market.

No, they have similar service intervals everywhere, even in the USA where it is more of a hindrance to sales than a marketing advantage. For this reason and for very low annual mileage drivers, VW gives a choice of regimes. It is possible to switch the variable service computer system off and to use a conventional fixed mileage interval of IIRC 10,000 miles/1 year using cheaper oil. There is no claimed advantage one way or another. It just gives the conservative a choice and the ultra conservative American compulsive 3000 mile oil changer can feel good about himself. It has been found that giving some consumers this choice actually causes much confusion. It is seldom possible to underestimate the intelligence of a group of car drivers or the population as a whole. If you doubt this theory then consider that my local Calor Gas supplier, a supplier of LPG, had a huge increase in orders today, illustrated by 24 orders on their answerphone this morning compared with an average of two, after a news item yesterday that some large scale CNG users might be rationed in extremely cold weather to keep electric generating stations feeding the grid on line.

Huw