I had an old friend who recently died. He always serviced his own car till about ten years ago, when he was no longer able. His wife was cleaning out the garage and she gave me all his old supplies. All of them ten or more years old. He had four gallons of Dexcool, twenty four quarts of 10w30 Pennzoil and various chassis lube. All of them sealed,unopened. Do any of these degrade after sitting so long? Are they still OK to use on my 99 Deville?

If the oil is designated as SH or SJ it has the older high-load additive package. Good stuff. Shake each bottle well. SL and SM are relatively recent.

Not sure about the DEX, but the old green coolants gradually lose color in storage and will go perfectly clear in a few years. What that means, I have no clue.

Grease is forever.