Question

What is `"SAE30"` oil?

Answer 1

This is a formulation issued by a professional body. SAE stands for "Society of Automative Engineers", as well as for self-addressed envelopes.

Explanation:

I found this link, which admittedly doesn't help me very much, but apparently it refers to viscosity and formulation. Apparently some engineers determined that this particular composition of engine OILS (i.e. it is a mixture) was optimal for engine performance in your Goggomobile. A typical engine oil is a long-chain hydrocarbon: `C_18H_38`, for instance. The longer the chain, the more viscous the oil. Long chain esters and olefins are also apparently used for lubrication. Of course there would be various additives in commercial samples.

Answer 2

SAE 15W40 lubricant is not a single chemical. It is a formulation which differs based on different product (though they provide same viscosity at given temperature range).

Explanation:

For example, Delo 400 LE SAE 15W-40 by Chevron contains:-
- 70-99 wt% Highly refined mineral oil (C15 - C50)
- 0.1-2.5 wt% Zinc alkyl dithiophosphate
- 0.1-1wt% Secret trade formula 01154100-5301P

The highly refined mineral oil are derived from lube oil processing plants in refineries. The facilities processes refinery stream containing C15-C50 (boiling point `300^oC-600^oC`) oil. So you can expect paraffinic (alkanes and cyclic paraffin) and aromatic (~5 wt%) constituent (as well as sulfur impurities (~10 ppm). For more info on lube oil processing, read http://www.machinerylubrication.com/Read/28960/mineral-oil-refining

Key
~ indicates that values are rough and not to be used as reference

References:-
[1] Delo 400 LE SAE 15W-40 MSDS http://s7d9.scene7.com/is/content/GenuinePartsCompany/1749936pdf?$PDF$
[2] Lubricant Base Oil and Wax Processing by Avilino Sequiera (pg 143)
[3] MINERAL OILS, UNTREATED OR MILDLY
TREATED Monograph, IARC, http://monographs.iarc.fr/ENG/Monographs/vol100F/mono100F-19.pdf