Tom R.

Has anyone read anything that says synthetic oil does not deteriorate rubber like dino does?

Doug Hillary

Hi Tom,
you have not had a reply so I help this helps
you. Please note too that very few seals are "rubber" and I presume seals are what you meant
Eaton Corp., the largest volume maker of gearboxes/diffs for trucks, said this in 1993;
"Fleet records have shown a failure rate of 1 seal every 150000 miles (average) during normal maintenance periods with mineral-based lubricants. During the same maintenance period trucks using >>>>>>>> synthetic lubricant have shown no evidence of leakage".

Many of my trucks have run 600000 miles on synthetics without leakage or replacement of seals

When changing from a much lessor API/ACEA rated non synthetic to a synthetic lubricant leakage may occur as the higher detergent action oil cleans off deposits on seal surfaces

In short, "brand" synthetics will not accellerate seal deterioration. Remember though that many of our cars are 10+ years old now

Regards

Tom R.

Doug,
Im more interested in the cooling system rubber.

thanks