what about conventional oil and addatives?

First time registered on this site and noticed your post regarding oil additives and the use of "teflon" products. First off, use the appropriate weight of oil specified by Toyota for your operating temperature range (Re: climate) and be sure to get the proper classification of oil (e.g., SG). I haven't a clue as to what is specified for this car, since my 2004 is still on order.

You do not need any oil additives. PERIOD! Use a quality dino or synthetic oil and change according to schedule. Often, people refer to 3,000 mile intervals (oil companies love to promote this...), but unless you drive alot of dirt choked roads, spend hours a day in stop and go traffic in a hot climate, or rarely get the oil up to operating temperature; this schedule is usually overkill. The Prius engine is designed to burn clean, and therefore is less likely to get the oil prematurely dirty (as compared to a 70's car).

Teflon products are snake oil at best. DO NOT USE THEM! I have had considerable experience (unfortunately) and have read extensive articles on the myth of Teflon oil products. For instance, did you know that Dupont sued for years to stop manufacturers from even mentioning Teflon? This was due to Dupont knowing their product was inappropriate for internal combustion engines! Listen to their Teflon ad claims and think through what they are claiming. I believe you will begin to smell a rat.

I will now step off my soapbox...

 

I agree completely. Today's oils are so good that none of that other stuff is necessary, especially on a cool running engine like the 1.5L in the Prius. It is still a common practice to load up an old car engine with STP to quiet it down just before selling it to some poor sap who doesn't know any better. Use a good dino, like Pennzoil or Castrol, or better yet, a good synthetic like Mobil 1 and your car will rust away before you have oil-related engine problems.