What engine oil do you use?

[Anorak_ian]

Hi guys,
I have always used 10w40 for diesels, but it's getting hard to find now (how odd), loads of shops stock 15w40 for diesels though. I was looking for 10w40 mineral for diesels but only found one, is mineral being fazed out for semi synthetic and full synthetic?

So what engine oil do you use and why?

Ian

[Eddy Wane]

Ian.
A quick trawl on the net has found loads of 10w40. ASDA do one, Halfords, Eurocar parts and there is one on eBay selling 25ltr drums for £60.
Eddy.

[Anorak_ian]

Yes I went to Halfords and they had only one (type and bottle of) 10w40 semi synthetic which is there own brand (I was looking for mineral), I also went to autocarparts no 10w40 on the shelves, the same at two other car accessory shops.
It just struck me as odd that most oils are synthetic (which is thin). I guess that shops stock the most popular oils.

I was more interested in what oil others use.
Ho hum write in haste repent at leisure.

[albertaphil]

Isn't a good oil supposed to be "thin" when it is cold and "thick" when it is hot? On the farm here we run 15w40 semi-syn in all the heavy diesels which either only run in the spring and summer or are in the heated shop. Everything else including automotive diesels get 0w30 semi-syn year round. Including my bike (for the couple of months It has been operational. )

I operate under the assumption that there is more damage to be done to an engine that makes many cold starts with thick oil than there is by hot (thin) oil simply not being able to keep the metal parts from contacting. My 2 cents.

[Anorak_ian]

I think the 30 or 40 after the weight (10w 15 w) has something to do with the heat thinning oil out, something to do with long chain polymers? I don't know I'm not an expert.

15w40 in the warm weather, yea, that's what I have used this time as I refuse to pay over the odds for 10w40 mineral. I'm only using mineral as I have recently found out that I have mistakenly run my new piston rings in with semi synth. So I'm going to give it a year on mineral. I'll change to a 5w40 full synthetic later.

I can understand the 0w30 for your harsh winters, all the metal parts shrink like a dick on DoDo's (some of you will know what I'm on about lol ). But once an engine has done with running in wouldn't full synthetic be a good choice?

[albertaphil]

My understanding is that the first number indicates the "weight" (really viscosity) of the oil at some cold temperature. The second number indicates the viscosity of the oil at a high temperature.

That is, 5w30 oil acts like 5 weight oil when cold but like 30 weight oil when hot. Of course, this does NOT mean that the oil is thicker when hot than when cold. It means that the viscosity of the oil does not drop as quickly when the temperature rises as does the viscosity of single weight oil.

I think your plan is a good one. Of I want so cheap id run full synthetic in everything all the time.