Maintenance Q&A
Extended oil drains and spring cleaning

By Paul Abelson, senior technical editor

Q. I saw that you mentioned in an earlier article adding replacement additives to oil when extending the drain interval. Where does one purchase such additives and detergents?

I am running a 2003 Peterbilt, with a C15 Caterpillar. It has 1.3 million miles on it, but I had a platinum rebuild done 60,000 miles ago. I use Rotella T6 oil. I run about 67 mph on average at about 1,400 rpm, and it’s all highway miles, no dirt or gravel.

I tried a bypass system in my old truck. It had an ISX engine. I switched to a centrifuge as I think it does a better job. It’s on my Cat now.

Since the rebuild, I add a gallon of oil between 5,000 and 7,000 miles, depending on how hard I have to run it. Mountain grades using the engine brake seem to lower it to 5,000 miles. On flatter terrain I get about 7,000.

Oil analysis comes back good after 15,000 miles when I change it about every six weeks. I would like to double that to 30,000, but without additives and detergents I would worry. I typically run 100,000 to 120,000 miles a year. That’s a lot of oil changes. However, given the cost of a rebuild, it’s cheap insurance.

A. With the recent rebuild, yours is effectively a new engine. The additional additives are in the makeup oil you add to the crankcase. Independent companies market so-called oil fortifiers or replenishers. The major producers of motor oils unanimously agree that such additives have the potential to upset the balance between chemicals in modern oils.

When the new PC-11 (proposed category) oils appear late next year, chemical balance could become a major issue.

After you wrote, we chatted on the phone. We discussed charting your oil analysis results to get a visual representation of trends or deviations from normal for your engine. These could be advanced warnings of developing problems even though the results are within limits. The trends are as important as the absolute results, maybe more so. You said the lab provides a graph of the oil testing results for you.

Results to track are:

Wear metal Normal up to Take action if above

Iron 100 ppm 200 ppm

Chromium 5 ppm 15 ppm

Aluminum 10 ppm 20 ppm

Tin 10 ppm 25 ppm

Lead 20 ppm 50 ppm

Copper 10 ppm 25 ppm

Make sure there are no sudden spikes or drops in results on the graph over time.

Make sure TBN (Total Base Number) is always higher than TAN (Total Acid Number). If TAN is higher, change oil immediately. As long as TBN is greater than TAN, you won’t need any additional additives.

Fuel soot should be low, especially since you are using a centrifuge-type bypass filter. Acceptable limits will be provided by the analysis lab.

To extend your oil drain interval from 15,000 miles to your target of 30,000, you need to rely on oil analysis. Take an oil sample without draining at 15,000 miles to make sure it’s safe to proceed. There are devices that screw into oil gallery plugs on the block or splice into the line leading to your centrifuge. Always sample before additional filtration. Then sample every 5,000 miles.

If you get to your target and there are no problems, that should be your new standard. Check everything at a few more oil changes. Do a sample at 15,000, 22,500 and 30,000 miles. On the next fill, sample at 20,000, 25,000 and 30,000 miles. Once you are comfortable with your new drain interval, just sample at 20,000 and again when you change oil.

If you are extending your drain interval, remember not to ignore other components that are interval sensitive like transmissions, axles and wheel bearings to name a few.

Q. Last year, I bought my first truck, a 2008 International. This past winter was brutal. I didn’t go three days without driving through snow somewhere. I live in Michigan and run mostly northeast and north central states.

Lots of chemicals got on my truck. I tried to wash it regularly, but if I went to the truck wash in the morning, I’d drive through more snow in the afternoon. The chemicals just piled up. Now that winter is over, I want to get all the remaining crud off, but I don’t trust the truck washes to do a thorough job. Any hints to pass along?

A. As with any endeavor, the quality of results depends on the skill and motivation of the operator. The chemicals that built up on your truck are eye, skin and respiration irritants. The proper way to remove snow removal chemicals involves equipment, procedures and personal protection.

Equipment can be rented. You’ll need a steam cleaner or a pressure washer, preferably both. I recommend using the pressure washer to remove any chemical residue. Pay special attention to any cracks in paint or crevices where salts can accumulate away from normal wash sprays. Some chemicals, especially calcium chloride, pull moisture from the air, create electrolytes, and promote galvanic corrosion. Steam should dissolve any residue not removed by pressure washing.

In Recommended Practice, RP536, “Guidelines for Technician Exposure to Road De-icing Chemicals,” the Technology and Maintenance Council recommends “that technicians use personal protection devices when working on equipment … operating in areas of the country that use corrosive deicers on road surfaces.” Devices include gloves, safety glasses or goggles, hats, long-sleeved shirts and dust masks or filters.

De-icing chemicals are tested in application concentrations, but buildups combined with other chemicals in unknown concentrations make toxicity levels difficult to determine. Play it safe. LL