by Robert Sanborn on Tue, Aug 29, 2006, who was a member of the STLE Society of Tribologists and Lubrication Engineers for 15 years.
I have a special by-pass filter that filters down to one micron and I am not going to change my oil until 500,000 miles on my truck. I change my regular full flow filter at normal intervals and my truck uses 3-4 gallons of motor oil during this interval. How much SFR should I use with the make up oil? Kelly Lackey, Lamar, Missouri
**Normally you would use 4-6 ounces per gallon of motor oil. Thus you would put in 12-24 ounces per drain interval. I would recommend the upper amount as not only does SFR have extreme pressure additives not found in motor oil, but it also contains more concentrated additive packages found in motor oil. One should be careful going a large number of miles and not changing their oil. Even though the by-pass filter will remove the vast majority of contaminants they do not account for additive depletion from the motor oil. Adding 3-4 gallons does not provide enough additives to treat the entire 13 gallons of motor oil that is in your truck. Additives do all of the work in a motor oil and get used up over time. **
**Motor oils contain corrosion inhibitors to fight water and fuel dilution, anti-oxidants to fight the affects of oxygen from the atmosphere that shortens the life of the oil, dispersants and detergents to fight soot and other contaminants, de-foamers to protect against foaming that ruptures film strength, anti-wear agents such as lubricity and boundary additives that are used up by sliding metal surfaces rubbing against each other over time. All additives get used up and adding make up oil to your engine is not enough for optimum protection. **
By adding SFR with its concentrated additives it will extend drain intervals but you should always use oil analysis because acids etc. can form that shorten the life of the motor oil depleting the additives ability to protect. This is why at SFR we have always recommend using SFR with each oil change. You should always beware of products that claim a one time treatment as not only is that dangerous there is no proof how long they will last. If you are going to extend your drain interval use a good oil analysis program to monitor your results.