Friday, Apr 02, 2004 at 21:25
evening Mark ..
i will be have to be very carefull here, as there are many varying opinions on this subject, and no matter what i say, i am bound to stirr up some reaction, but what the heck, here goes.
Synthetics (general) .....
Firstly, there is more than one type of "synthetic", and it must be remembered that when we use the tern synthetic, we are generally referring to the base oils used in the finished product.
Synthetic base oils start at Group 3 hydrocracked paraffinics through to group 5 PAO's (don't ask me to spell it, or i will have to look it up).
Now the general inference is that synthetics are man made as oposed to mineral oils refined from the ground and mostly produced as group 1 base oils. Group 2 base oils in the main are paraffinics taken one step further by hydrocracking (hydromerised, hydrotreated etc) to produce a "better" base oil with a vscosity index (VI) between say 105 and 120.
Once we go past 120 VI by further treatment, we are into the group 3 synthetic base oils.
when we go past there and into group 4 and 5 synthetics we are into things like esters and PAO's (there it is again).
Synthetics do have higher natural Viscosity Index and do stand up to heat, oxidation, shear etc better than mineral base oils, so from this we can expect them to do a better job and last longer under harsher conditions.
Now many believe that when it comes to subjecting the various base oils to mechanical shear, that synthetics hold up much better, but also say that when a synthetic oil shears, it does so with little warning.
A mineral oil will shear quicker but at a more predictable rate.
Horses for courses also as synthetic products are more expensive than mineral products, but in the main do perform a lot better.
Having said all that, with gear lubes, it is possible to overtreat a mineral base oil with sufficient additive and have it out perform a synthetic, as the service change will come arround
well before the mineral lets go.
There has been a lot of talk or reservation about synthetics when it comes to "seal swell" (something we must have to keep the seals tight on shafts etc) in that synthetics did not provide enough swell like minerals oils naturally do. Additive companies have been working this though and claim to now have an additive to help here.
As a general summary, i believe synthetics are better and will last longer offering more protection.
Most new vehicles are not filled with synthetics unless the manufacturer thinks their product needs the extra help.
The best i can do is say what i know and offer my opinion in the hope that others will form their own.
regards to all, russell
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