Jump to content

engine oil


Tonk

Recommended Posts

need to get some engine oil for my 200tdi, phone motor factors and asked for 15/40 semi-synthetic, he said he hasn't got any and its not made anymore, he offered mineral 15/40 and thats it. am i askin for the right spec oil? can i run a different spec? or is he just a numpty?

Link to comment
Share on other sites

Aye good quality oil is Halfords stuff. Better than some of the big names, and cheaper too.

:ph34r:

I'm with Mark on this

And they have a list telling you what each engin can run one if your feeling rich or the cheepest if you not so flush.

Good with a V8 because they tell you what the change over piont is from 20/50 to 5/40 and 0/30 :blink:

Link to comment
Share on other sites

I tried running a thinner oil (5W30 IIRC) and had no end of problems with the oil pressure light staying on when the engine was up to heat. Now switched back to 15W40 and no further problems.

Link to comment
Share on other sites

I tried running a thinner oil (5W30 IIRC) and had no end of problems with the oil pressure light staying on when the engine was up to heat. Now switched back to 15W40 and no further problems.

My TD5 disco is good as gold on 5W30

Link to comment
Share on other sites

Jules the Td5 is supposed to have 5w30 though, as is the Thor V8 my Discovery has.

I don't think I would put it in any of the older engines if what is specified is 15w40, not unless you lived inside the Arctic circle or something anyway!

Link to comment
Share on other sites

Mineral is the thickest oil at running temp

semi-synth next

synthetic is the thinnest

if in doubt ring your stealer and then go buy the cheapest

last time I needed oil of my TD (mineral) it was the dealers that were the cheapest so I bought it there

Link to comment
Share on other sites

Mineral is the thickest oil at running temp

semi-synth next

synthetic is the thinnest

if in doubt ring your stealer and then go buy the cheapest

last time I needed oil of my TD (mineral) it was the dealers that were the cheapest so I bought it there

Siggy, Siggy, Siggy, how on earth do these hoary old myths perpetuate.......... <_<

Let us compare three diesel oils, one a full mineral 15W-40, in this case Mobil Delvac MX, the next a semi-synthetic 10W-40, Mobil MX Extra and lastly their full synthetic cousin in 5W-40, Mobil Delvac 1.

I'm using these as I have the specs in the 'puter.

First things first, actual viscosity of warm engine oils is measured in centiStokes (cSt). To be classified as an xW-40, our oil must have a viscosity in the range of 12.5 cSt @ 100*C to 16.3 cSt @ 100*C. (there are other measurements, such as the shear rate [HTHS] that are also specified and I'll ignore for the moment)

Now lets look at our three examples at 100*C.

Delvac MX is 14.2 cSt

Delvac MX Extra is 14.2 cSt

Delvac 1 is 14.8 cSt

OK, our Delvac 1 is the thickest (just) of these three at 100*C, but wait, there's more !

There is a measure of how an oil thins (reduces viscosity) with increased temperature and it is called its viscosity index. The higher the number, the less it thins.

Delvac MX VI 138

Delvac MX Extra VI 135

Delvac 1 VI 151

These numbers show that as the oil temperature exceeds 100*C, the Delvac 1 will thin less than the other two oils.

This is a very simplified explanation, and I've deliberately not tried to explain what happens at the other end of the scale to avoid further confusion. ;)

Link to comment
Share on other sites

This seems a good moment to roll this out again

Chris

Chris, there's some good information on that link, some things ignored/overlooked, (eg. two major groups of oils, Group V, which comprise Synthetic base oils such as the esters [di and polyol, think Redline, Silkolene, Fuchs, Motul, et al and generally blended in various proportions with PAO's to give certain characteristics] and alkylated napthalenes, which have supplanted esters in Mobil 1, and Group III oils, which are derived from mineral oils, but have been severely hydrocracked, refining them further and mimicking a lot of the characteristics of a synthetic for less production cost, and often labelled as a synthetic in the US and Oz. In Europe these are labelled such as 'Technosynthese' or 'Molecularly Converted') some things I disagree with and some absolute hokum such as PAO's being derived from mineral oil (they are actually derived from ethylene gas) ;)

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...

Important Information

We use cookies to ensure you get the best experience. By using our website you agree to our Cookie Policy