• Why is ZDDP important now? I've never heard of it!
  It's no surprise that the majority of people have not heard of ZDDP. ZDDP (zinc dialkyldithiophosphate) has been a primary ingredient of motor oils for decades, silently doing the job for which it was designed - that of protecting our camshafts and lifters from metal-on-metal contact. As part of an effort to reduce vehicle emissions, the U.S. EPA offers vehicle manufacturers "credits" for early implementation as well as penalties for violation of emission reduction standards. The EPA's program called for 100,000-mile catalytic converter life by 2004, 120,000 miles by 2007, and 150,000 miles by 2009. To meet these goals, auto manufacturers have pressured oil suppliers to remove compounds from the oil which cause a shortened service life of the catalytic converter. Zinc and phosphorus from the ZDDP can be present in small amounts in the exhaust gas of an engine depending on the amount of oil which is consumed in combustion. These elements can coat the catalyst reducing the amount of catalyst exposed to the exhaust gases, ultimately increasing emissions at the tailpipe. As a result of the EPA mandate, the ZDDP level in engine oils has been declining since the mid-1990s, roughly coinciding with the implementation of OBDII.Back to top
  
  
• How do I know if I need ZDDPlus?
  In General, if your vehicle was produced before 1996, or if you know that the camshaft/lifter combination in your vehicle is of a 'flat tappet' design, you will need ZDDPlus. An engine utilizing 'roller lifters' will not require ZDDPlus.Back to top
  
  
• How is ZDDPlus shipped?
  Orders that contain a quantity of up to 30 bottles of ZDDPlus are shipped via USPS "Priority Mail Flat Rate Box" service. Quantities of greater than 30 bottles are shipped via UPS Ground service. In exploring the least expensive shipping methods possible, we've determined these to be the most cost effective.Back to top
  
  
• Do you have a return policy?
  Yes, we will gladly take your order back if you have changed your mind. Simply call us, or send us an email, explaining the reason for the return. Even though we offer free shipping, the shipping does cost us normal rates, therefore, we will need to subtract that shipping cost from your refund. You may return the product using the shipper of your choice (we will not accept COD shipments). All product returned must be un-opened with the foil seals in place, and in like new condition.Back to top
  
  

l Determining The Type of Lifter Used in Your Engine...
If you need to determine the type of lifter your car or truck's engine uses, you can use this link which will open a new window. This new window is the NAPA Auto Parts website. It will ask if you are shopping for a part for a specific vehicle: Click on the "Yes" box. Simply click on your vehicle Year, Make, and Model.

A new window will appear. In the first white box type in "Valve Lifter", and click on 'SEARCH'. An image and description of the lifter in your engine will be presented. If the lifter type shown for your engine is 'Hydraulic flat tappet', or 'Mechanical flat tappet', ZDDPlus is required in your engine.... it's that simple! Remember, overhead cam motors, in most cases, utilize bucket-type followers which will not require the use of ZDDPlus.

For you boat owners we have found a website that can guide you to the type of valve lifter used in your engine. This website, MarineEngine.com, appears to have a thorough listing. Please click on the make of your boat engine, then navigate to the appropriate section. Please note that we have noticed that not all lifter types are listed for all engines.