I only use full synthetic motor oil in my engine due to its superior properties. Vote for your choice let us know how you fill.

i use synthetic in my wife's car, and blend in my exploder and the Z. i was thinking of switching to full synthetic in the Z but with 75,000 mi and no leaks other than the one i fixed. i dont want the car to start pissing oil on my driveway again.]

i use synthetic in my wife's car, and blend in my exploder and the Z. i was thinking of switching to full synthetic in the Z but with 75,000 mi and no leaks other than the one i fixed. i dont want the car to start pissing oil on my driveway again.]

If you did decide to go with a synthetic, Mobil 1 HM would be good choice. On my wife's vehicle which is a 2000 Neon I use Pennzoil HM 5W30 in hers with 4000 mile oil changes. I currently have Royal Purple motor oil in mine.

Lubricant base stocks are categorized into five groups by the API.

Group I base stocks are composed of fractionally distilled (http://en.wikipedia.org/wiki/Fractional_distillation) petroleum (http://en.wikipedia.org/wiki/Petroleum) which is further refined with solvent extraction processes to improve certain properties such as oxidation resistance and to remove wax.

Group II base stocks are composed of fractionally distilled (http://en.wikipedia.org/wiki/Fractional_distillation) petroleum (http://en.wikipedia.org/wiki/Petroleum) that has been hydrocracked (http://en.wikipedia.org/wiki/Hydrocracking) to further refine and purify it.

Group III base stocks have similar characteristics to Group II base stocks, except that Group III base stocks have higher viscosity indexes. Group III base stocks are produced by further hydrocracking of Group II base stocks, or of hydroisomerized slack wax, (a byproduct of the dewaxing process).

Group IV base stock are polyalphaolefins (http://en.wikipedia.org/wiki/Polyalphaolefin) (PAOs). A synthetic.

Group V is a catch all group for any other synthetic and mineral base stocks. Examples of group V base stocks include polyol (http://en.wikipedia.org/wiki/Polyol) esters (http://en.wikipedia.org/wiki/Ester), polyalkylene glycols (http://en.wikipedia.org/w/index.php?title=Polyalkylene_glycol&action=edit) (PAG oils), and perfluoropolyalkylethers (http://en.wikipedia.org/w/index.php?title=Perfluoropolyalkylether&action=edit) (PFPAEs).

Groups I, II, and III are sometimes referred to as mineral oils (http://en.wikipedia.org/wiki/Mineral_oil) and groups IV and V as synthetic oils (http://en.wikipedia.org/wiki/Synthetic_oil). However, most manufacturers have labeled their group III based oils as synthetic in the US for reasons of economy and marketing.