I clearly have nothing better to do this evening, so here's a short essay on oil. Christ you're in for a thrilling read! (if the alternative is washing up
)
Sounds promising, at least it won't be a 0W or 5W.
Not that you chaps don't know, but for Remington rolling block's info
The "5w or 10w" number is the SAE viscosity rating when cold - i.e how well the oil flows (its relative density) at cold start, a lower number means the oil is thinner
comparatively to a higher w number. But remember, this applies for comparative purposes only when the oil is
cold.
The " 30 or 40" number is the SAE rating at 100c ~, running temperature essentially. This number indicates the oil viscosity will not thin past a minimum value attributed to that weight or be thicker than a set value, normally measured in square millimeters traveled per second, often referred to as Centistokes per second (kinematic flow rate). (mm2/s or cSt) - it is a lot more complicated than this of course, a cheap semi synth 40 weight (the 40 being attributed owing to the "kinematic" flow viscosity, as I just mentioned above), will potentially have a worse shear rate (i.e loses lubricity more easily and provides less slipperiness) than a 30 weight high quality synthetic oil, owing to how the same test applies to oils that can be poles apart in terms of chemical make up.
In essence = there is (from a sales point of view) no viscosity difference between a 5w-40 or a 10w-40
once the engine is hot, both will have a flow characteristic
within the SAE 40 weight tolerances (when new anyway) - but keep reading, as while the previous statement is true, as is the statement "a 15w-40 oil can be thicker than a 5w-40 oil".
Cold example = When cold, a 5w-40 oil will be "thinner" than a 10w-30 - however once hot, the 10w-30 will have thinned out more than the 5w-40 weight oil. These examples are in difference tolerance categories and thus is always the case.
Interesting part nobody ever actually knows: The hot ratings are variables with a fair tolerance range and it is quite common for a 0w-40 to be thinner at operating temperature than say a 15w-40 (even though that's not how they sell or label it), as the "cold" measurement is a
set minimum value. a good example is than the "minimum" flow value for a 5W rated oil is 3.8mm2/s, i.e when dropped it covers 3.8mm of distance each second, whereas a 15W has a minimum value of 5.6mm2/s. 40 weight spec demands minimum flow of 12.5mm2/s, and a maximum flow of less than 16.3mm2/s, so not a set amount
Product example:
Comma X-flow type G 5w-40 Fully synthetic = viscosity @ 100c is 13.4 mm2/s
Castrol GTX 15w-40 Semi-synthetic = viscosity @ 100c is 14.32 mm2/s
If you remember from earlier, the minimum value flow rate difference between 5w and 15w's is 0.8mm2/s - and the "hot" values of these two oils is around that amount different (this is not a given but a handy example I could find on sale now), so the GTX is
THICKER than the X-flow, even though they're both 40 weights. Great bit of pub knowledge for the average petrol head having an oil argument, 5 pints and retirement required for the conversational quality to drop this far with your old mate
Yet another point if you're still reading - the W weight is often provided on the data sheet as the density of the oil @ 15c (give or take) or the "cold cranking viscosity value", measured in centimeters cubed / grams per milliliter (same value). so the same products from earlier:
Comma: 0.853g/ml @ 20c
Castrol: 0.871g/ml @ 15c (data sheets had 5c different test values, sorry )
So the actual real world difference between these two oils is less than 10%, when cold, and less than 10% when hot - but ironically the hot difference is about the same as the cold difference even though the cold weight numbers are very different and hot numbers exactly the same! Very misleading essentially
Edit: Another good example is the weight difference between say, a 40 engine oil and a 90 gear oil - test conditions are slightly different but both are actually very similar viscosity @ 100c. Hence why Redline MTL 80w-90 says it meets SAE 30 on the back, if you've ever wondered!
Real engine damage occurs not so much with the wrong oil viscosity (unless you stick a 20 weight in the landy), but the wrong grade of oil - a DI turbo diesel isn't going to be very fond of an A1/B1 grade oil you found in the shed from years past, no matter the viscosity.
Short version: Stick some decent 10w-40 in it boyo
Source: many hours reading about oil when I got my first ****er rotary car on sites such as bobistheoilguy.com, viscopedia.com with data sheets just coming from respective websites
