I do it. I use Mobile 1 fully synthetic oil and substitute a quart with the lucas oil. Been doing it for about 2 years and my cars still running like a champ, 01 Grand am. Got it with 35k miles and its up to 120k already.
Lucas also makes a synthetic engine oil additive.. Yes.
Use no oil additive. It is a waste of money and might actually do harm.
Dealer reccomends their stuff, I use Royal Purple fully synthetic/Mobil 1 or Lucas fully synthetic will do
Yes
No, old oil can use synthetic engines
yes you can use synthetic oil if you want to
You can use synthetic, synthetic blend, or conventional oil. It is your choice.
80W90 in both use lucas or some type of synthetic like redline.
Yes. Marvel mystery oil is fully compatible with synthetic oil.
Synthetic oil.
You can use Lucas oil treatment in just about any type of oil. I use it with Valvoline high mileage.
Yes you can use synthetic oil in a 97 Escort.