Engine oil query

[Marco]

Guys,

Just a bit of advice required from anyone who's experimented with these things... My Merc C320 CDi is due for an MOT next week, and so when it's in there I'd like to have the oil and filter changed too, as mileage wise, it's just about due.

So, the question is: what's the difference between 0W-30, 0W-40, 5W-30 and 5W-40 oils - all of which my car can take? I know it's something to do with a temperature/viscosity thing, but could do with more info.

Also, do any of the types above give better performance, in terms of engine responsiveness? That's also a consideration for me, as well of course as ensuring proper protection. I read somewhere that the thinner oils can sometimes be better, in terms of the former. Is that true - and if so - what's it based on?

Lastly, has anyone compared Castrol Edge FST, shown here: http://www.opieoils.co.uk/p-713-castrol-edge-5w-30-fst-fully-synthetic-engine-oil.aspx with Shell Helix Ultra Extra, shown here: http://www.opieoils.co.uk/p-68973-shell-helix-ultra-extra-5w-30-premium-fully-synthetic-engine-oil.aspx

I will be using one or the other, and currently am veering towards the 5W-30 versions.

All input appreciated! :cool:

Marco.

[Ali Tait]

I use Edge in my Alfas Marco, no complaints here.

Good explanation on viscosity here-

http://www.kewengineering.co.uk/Auto_oils/oil_viscosity_explained.htm

[Marco]

Thanks for the link, Ali. I'll have a good read of that :)

In terms of engine responsiveness/performance, have you noticed any difference between, say, a 5W-30 oil, compared to a 5W-40, or even an 0W-30? And which type do you use?

The link you provided will give me all the info I need, in terms of ensuring the right protection for the engine, but I'm trying to get a handle on whether or not there are any (albeit small) performance gains between using the above viscosity types, even theoretically?

Churz! :cool:

Marco.

[Ali Tait]

Not that I've really noticed, though of course it may be different for diesels?

[Marco]

No worries, matey. Anyone else? :)

It would be interesting to hear Martin T's input on this, as I suspect he's experimented with his Beemer, or indeed anyone who drives a C320 CDi (or similar).

Marco.

[Audio Al]

I use 5w - 30 in my car full synthetic

The viscosity rating is also relevant to the inner working of the engine ( hydraulic tappets ) engines can be noisy if the wrong oil is used

I assume you know the 5 and the 30 are cold and hot oil viscosity ratings ( measured running down a slope over a set distance under test conditions )

[archiesdad]

Castrol Edge turbo diesel, here
http://www.opieoils.co.uk/p-719-castrol-edge-turbo-diesel-fst-5w-40-advanced-synthetic-engine-oil.aspx
is highly recommended on the owners club I frequent and we use it in high revving petrol *engines, there are oils that claim performance improvements but a test I saw showed very small gains for the money and to my mind not worth it.

* Apparently had to be badged suitable for diesels otherwise owners of diesels wouldn't buy it, info from a castrol employee.

[MCRU]

Brooksy to the rescue again, Shell, Mobil, Esso are all run of the mill lubricants which do the job but there is better than run of the mill.

The best lubricants or up there with the best is Omega.

Contact is Tim if you want the best, I suspect you will. I put Omega in with my diesel every time I fill up my van.

Here (http://www.sovereign-omega.co.uk/)is the website.

The rolls royce of lubricants, like duracell batteries, cost 3 times more but last 10 times longer. :)

This is what you need to put in your fuel tank (diesels only) each time you fill her up

Omega 903 (http://www.sovereign-omega.co.uk/Datasheets/Omega903-1.pdf)

[tommy6206]

5W-30 winter and 5W-40 summer if its a high miler I would go 5w-40 all year

[Marco]

Thanks, chaps. Reading the info contained in the link, supplied by Ali, this is the bit that interests me most:


The viscosity will determine how easily the oil is pumped to the working components, how easily it will pass through the filter, and how quickly it will drain back to the engine. The lower the viscosity the easier all this will happen. That is why cold starts are so critical to an engine because the oil is cold, and so relatively thick.

But, the lower the viscosity, the less the load the oil can support at the bearing on the crankshaft. The higher the viscosity, the better the load it can support. Even this, however, has a trade-off, since the higher the viscosity, the more the drag at the bearing, and hence, potential power loss, or increased fuel consumption. So a compromise is chosen to minimise power loss, but maximise load support.

For domestic use, engine life is important, and in the main you should adhere to the recommended viscosity for your engine. For motorsport, engine life is not critical, winning is, so these high performance engines can use lower viscosity oils to maximise power output to the wheels...


The bits highlighted in blue clearly indicate that there are performance benefits from using a certain viscosity of oil (low) - *BUT*, outside of motorsport, a correct balance must be achieved between performance and protection and, as the article says: "a compromise chosen to minimise power loss, but maximise load support."

To that extent, I have decided to go with 5W-30 (as I consider it offers the best compromise), and so have ordered 7 litres (the required amount for my car) of Shell Helix Ultra Extra. I like how it is described:

"For maximum responsiveness and improved performance, enabling your engine to operate at its full potential right up to the next oil change. Shell Helix Ultra Extra is a unique, fully synthetic lubricant giving ultimate engine and exhaust after treatment protection for performance motoring...", together with the fact that it is approved by Mercedes Benz.

Furthermore, I have found some at a good price, from this seller on ebay (offering free P&P): http://www.ebay.co.uk/itm/Shell-Helix-Ultra-Extra-5w30-Engine-Oil-SHE-087-7-1x5L-2x1L-7-Litre-/161101628562

Job done! :)

I'm picking up a new oil filter from the Merc dealership on Monday, and will give the lot to my local mechanic to use, after sorting out the MOT.

Marco.

[Marco]

Brooksy to the rescue again, Shell, Mobil, Esso are all run of the mill lubricants which do the job but there is better than run of the mill.

The best lubricants or up there with the best is Omega.

Contact is Tim if you want the best, I suspect you will. I put Omega in with my diesel every time I fill up my van.

Here (http://www.sovereign-omega.co.uk/)is the website.

The rolls royce of lubricants, like duracell batteries, cost 3 times more but last 10 times longer.

This is what you need to put in your fuel tank (diesels only) each time you fill her up

Omega 903 (http://www.sovereign-omega.co.uk/Datasheets/Omega903-1.pdf)

Thanks for that. I may give the Omega 903 stuff a go :)

Marco.