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Guest matt25011774

what oil does it take

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Sounds like you got worked out John, would agree with you above comments entirely.

Once on full synth, you can go back to semi or even mineral, not without checking but most motor oils are now compatable with each other.


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Just done a full service on my x11, as nosmal the oil came out like new, its now got 3.9l of the finest castrol fully synthetic, was told this was the best.

Take care


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More stuff on oils, confused yet?

Mixing Mineral and Synthetic oils - the old and busted concepts

  • If you've been driving around with mineral oil in your engine for years, don't switch to synthetic oil without preparation. Synthetic oils have been known to dislodge the baked-on deposits from mineral oils and leave them floating around your engine - not good. I learned this lesson the hard way! It's wise to use a flushing oil first.
  • If you do decide to change, only go up the scale. If you've been running around on synthetic, don't change down to a mineral-based oil - your engine might not be able to cope with the degradation in lubrication. Consequently, if you've been using mineral oil, try a semi or a full synthetic oil. By degradation, I'm speaking of the wear tolerances that an engine develops based on the oil that it's using. Thicker mineral oils mean thicker layers of oil coating the moving parts (by microns though). Switching to a thinner synthetic oil can cause piston rings to leak and in some very rare cases, piston slap or crank vibration.
  • Gaskets and seals! With the makeup of synthetic oils being different from mineral oils, mineral-oil-soaked gaskets and seals have been known to leak when exposed to synthetic oils. Perhaps not that common an occurrence, but worth bearing in mind nevertheless.

Mixing Mineral and Synthetic oils - the new hotness

That's the thing with progress - stuff becomes out-of-date. Fortunately for you, dear reader, the web is a great place to keep things up-to-date, so here's the current thinking on the subject of mixing mineral and synthetic oils. This information is based on the answer to a technical question posed on the Shell Oil website.

There is no scientific data to support the idea that mixing mineral and synthetic oils will damage your engine. When switching from a mineral oil to a synthetic, or vice versa, you will potentially leave a small amount of residual oil in the engine. That's perfectly okay because synthetic oil and mineral-based motor oil are, for the most part, compatible with each other. (The exception is pure synetics. Polyglycols don't mix with normal mineral oils.)

There is also no problem with switching back and forth between synthetic and mineral based oils. In fact, people who are "in the know" and who operate engines in areas where temperature fluctuations can be especially extreme, switch from mineral oil to synthetic oil for the colder months. They then switch back to mineral oil during the warmer months.

There was a time, years ago, when switching between synthetic oils and mineral oils was not recommended if you had used one product or the other for a long period of time. People experienced problems with seals leaking and high oil consumption but changes in additive chemistry and seal material have taken care of those issues. And that's an important caveat. New seal technology is great, but if you're still driving around in a car from the 80's with its original seals, then this argument becomes a bit of a moot point - your seals are still going to be subject to the old leakage problems no matter what newfangled additives the oil companies are putting in their products.

Flushing oils

These are special compound oils that are very, very thin. They almost have the consistency of tap water when cold as well as hot. Typically they are 0W/20 oils. Don't ever drive with these oils in the engine - it won't last. (Caveat : some hybrid vehicles now require 0W20, so if you're a hybrid driver, check your owner's manual). Their purpose is for cleaning out all the gunk which builds up inside an engine. Note that Mobil1 0W40 is okay, because the '40' denotes that it's actually thick enough at temperature to work. 0W20 just doesn't get that viscous! To use them, drain your engine of all it's oil, but leave the old oil filter in place. Next fill it up with flushing oil and run it at a fast idle for about 20 minutes. Finally, drain all this off (and marvel at the crap that comes out with it), replace the oil filter, refill with a good synthetic oil and voila! Clean engine.

Of course, like most things nowadays, there's a condition attached when using flushing oils. In an old engine you really don't want to remove all the deposits. Some of these deposits help seal rings, lifters and even some of the flanges between the heads, covers, pan and the block, where the gaskets are thin. I have heard of engines with over 280,000km that worked fine, but when flushed it failed in a month because the blow-by past the scraper ring(now really clean)contaminated the oil and screwed the rod bearings.

Using Diesel oil for flushing

A question came up some time ago about using diesel-rated oils to flush out petrol engines. The idea was that because of the higher detergent levels in diesel engine oil, it might be a good cleaner / flusher for a non-diesel engine. Well most of the diesel oil specification oils can be used in old petrol engines for cleaning, but you want to use a low specification oil to ensure that you do not over clean your engine and lose compression for example. Generally speaking, an SAE 15W/40 diesel engine oil for about 500 miles might do the trick.

A quick guide to the different grades of oil.

Fully SyntheticCharacteristics0W-30


5W-40Fuel economy savings

Enhances engine performance and power

Ensures engine is protected from wear and deposit build-up

Ensures good cold starting and quick circulation in freezing temperatures

Gets to moving parts of the engine quicklySemi-syntheticCharacteristics5W-30


15W-40Better protection

Good protection within the first 10 minutes after starting out

Roughly three times better at reducing engine wear

Increased oil change intervals - don't need to change it quite so oftenMineralCharacteristics10W-40

15W-40Basic protection for a variety of engines

Oil needs to be changed more oftenSo what should I buy?

Quality Counts! It doesn't matter what sort of fancy marketing goes into an engine oil, how many naked babes smear it all over their bodies, how bright and colourful the packaging is, it's what's written on the packaging which counts. Specifications and approvals are everything. There are two established testing bodies. The API (American Petroleum Institute), and the European counterpart, the ACEA (Association des Constructeurs Europeens d'Automobiles - which was the CCMC). You've probably never heard of either of them, but their stamp of approval will be seen on the side of every reputable can of engine oil.

The API api_logo.gifThe API classifications are different for petrol and diesel engines:

  • For petrol, listings start with 'S' (meaning Service category, but you can also think of it as Spark-plug ignition), followed by another code to denote standard. 'SM' is the current top grade, which recently replaced 'SL' and 'SH'. 'SH' will be found on most expensive oils, and almost all the new synthetics. It's basically an upgraded 'SG' oil which has been tested more sternly.
  • For diesel oils, the first letter is 'C' (meaning Commercial category, but you can also think of it as Compression ignition). 'CH' is the highest grade at the moment, (technically CH-4 for heavy-duty) but 'CF' is the most popular and is well adequate for passenger vehicle applications.

Note about Castrol oils: Castrol have recently upgraded all their oils and for some reason, Castrol diesels now use the 'S' rating, thus completely negating my little aid-memoir above. So the older CC,CD,CE and CF ratings no longer exist, but have been replaced by an 'SH' grade diesel oil. This link is a service bulletin from Castrol themselves, explaining the situation. The CCMC/ACEA acea.gifThe ACEA standards are prefixed with a 'G' for petrol engines and a 'D' or 'PD' for diesel. Coupled with this are numerous approvals by car manufacturers which many oil containers sport with pride. ACEA replaced CCMC in 1996 primarily to allow for greater read-across in test programs (eg. for viscosity, viscosity modifiers and base oil). The CCMC specifications were G (1 to 5) for gasoline, D (1 to 5) or heavy duty diesel and PD1 and PD2 for passenger car diesel. ACEA though have a slightly different nomenclature they can be summarised as A for petrol, B for passenger car diesel and E for heavy duty diesel. The ACEA grades may also be followed by the year of issue which will be either '96, '98 (current) but coming soon is 2000.

Full ACEA specs are:

  • A1 Fuel Economy Petrol
  • A2 Standard performance level
  • A3 High performance and / or extended drain
  • B1 Fuel Economy diesel
  • B2 Standard performance level
  • B3 High performance and / or extended drain
  • B4 For direct injection passenger car diesel engines
  • E1 Non-turbo charged light duty diesel
  • E2 Standard performance level
  • E3 High performance extended drain
  • E4 Higher performance and longer extended drain
  • E5 (1999) High performance / long drain plus American/API performances. - This is ACEAs first attempt at a global spec.

Typically, these markings will be found in a statement similar to: Meets the requirements of API SH/CD along the label somewhere. Also, you ought to be able to see the API Service Symbol somewhere on the packaging:


If this is all confusing you, then rest assured that all top oils safely conform to the current standards. What you should treat with caution are the real cheapies and those with nothing but a maker's name on the pack. Anything below about

Edited by wayne

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A very important warning to those reading the flushing oil section, do not use diesel engine oil to do the flushing through in your X11, as Eddy will tell you, diesel engine oil will dissolve your clutch friction plates! :eek:


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Just replaced my oil and filter. Will be doing it every 4000 miles. Used Castrol Actevo.



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You can use mineral oil after using fully synthetic. Otherwsie, they wouldn't make semi-synthetic, which is already mixed.

As for which one to use, it is a personal choice, really. The trick is changing it often, as well as the filter. I also change both every 3K - for the few quid it costs it's well worth it to me.


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Wrote that before reading Wayne's email. Yes, thing with it is that progress always moves forwarda s we learn more. I always use semi-synthetic, myself. Prefer Castrol Actevo, too.


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I change my fully synthetic and filter every 3k. Oil is the lifeblood of your engine, so it pays to use the best. Car oils will cause slip, but motorcycle specific won't.


I use 1040 fully synthetic and a can of slick 50 for every change! a bit on the expesive side i know but its ma baby and as plastic Orange says its her life blood so best money can buy!:eek:

Before anyone says anything about the slick 50 i fully belive in it had have seen some proper controled tests with it and they were very impresive ;)


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This oil post seems to have caught the imagination !!!

I change oil / filter every 3000 miles...used various makes since ownership, and currently using Comma fully synthetic Syner-G.

As I am doing about 500 miles a week,plenty of experience on oil changes !!! :D

Current oil (


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