When a straight mineral oil turns dark or black, it usually means that the oil is starting to oxidize and needs to be changed. Because mineral oil doesn’t absorb much of the dirt and sludge in your engine, the oil stays clean and the inside of your engine gets dirty. Ashless dispersant oils, on the other hand, are designed to get dirty so that the engine will stay clean. 

Just how quickly the oil turns black depends on a number of factors, including the condition of the engine, the dirt load, the oil temperature, the normal air/fuel mixture, the type of fuel, the time since the last service, and the frequency and duration of your flights. Basically, the important thing to remember is to change your ashless dispersant oil on calendar and engine time, not according to its color. Also, oil analysis can help ensure that the oil is still in good condition even though it may have turned black.

In most cases, the multigrade oil will run cooler. For a hot-running engine, like turbocharged, high performance or aerobatic aircraft engines, this is good, but for a cool-running engine it can be a disadvantage. If the engine runs too cool, it can't boil off excess moisture and unburned fuel, so there can be a tendency to form acid buildup. For cooler-running engines, pilots should use a winterizing kit, or check with their mechanics on how to keep oil temperature up.

Yes. The thickness, or viscosity, of an oil is directly affected by the temperature. Therefore, if an engine's oil temperature is increased, there will be a small, but proportional, drop in the oil pressure as well.

A number of pilots have asked this question. The answer is a definite no. When Shell first started evaluating multigrade aviation piston-engine oils over 25 years ago, testing proved that multigrades formulated only with mineral base oils did not have adequate base oil viscosity (thickness) to properly lubricate all high load points in the engine. Then we tested and flight evaluated a formulation made with all-synthetic base oils.

This formulation had excellent antiwear characteristics in all tests run. However, in the flight evaluations, some engines would reach 600 to 900 hours, then lose oil consumption control and/or compression. When the engines were disassembled, we found that the piston rings were covered with a gray tacky substance that was primarily made up of the lead by-products of combustion (from the use of leaded aviation gasoline).

Although synthetics are excellent lubricants with good high temperature stability and very good low temperature flow characteristics, they are relatively poor solvents.

In an aircraft engine, the lead by-products of combustion must be dissolved by the base oil so they can be carried away from the ring belt area and removed from the engine when the oil is changed. Anticorrosion, antiwear AeroShell Oil W 15W-50 is formulated with 50% synthetic base oils to give it the excellent low temperature flow needed for quick lubrication during cold starting. 

The synthetic base oils, along with the unique antiwear additive system, give it antiwear protection unequaled by any other product on the market. In addition, its mineral base oils provide lead absorbency to guard against ring sticking and excessive sludge. The bottom line: The synthetic component of AeroShell Oil W 15W-50 will not harm your engine. Instead, it gives you the best of both oils.

Per the manufacturer, Plane Power alternators do not include capacitors.

They are sold in pairs and are one position per price. 

No, they will only include the bushing. All mounting hardware will need to be purchased seperately.

Yes, the hole for the grouding strap is drilled and tapped, ready for strap installation as necessary. 

Typically, you will feel unusual vibrations when you start your aircraft's engine, accompanied by loud clanking and banging from the engine bay. 

There are several ways of repairing worn cowl surfaces. Epoxy fill is sometimes used for minor wear, or flush or double flush riveted aluminum doubler plates can be formed and installed over the damage. McFarlane has a high temperature (400deg F) sandable two part epoxy with an aluminum filler that works well for filling minor cowl skin defects; please see P/N 20 GLUE KIT. Consult with your A&P mechanic for the best repair solution for your aircraft.

There is not a concrete answer that will work for every customer; it really depends on each individual installation. As a general rule, as long as you do not put the rivets at the very edge of the material it will not rip out. If you use McFarlane’s retainer strips, they can line up the edge of the material with the bottom of the retainer strip and then put the rivets in the middle of the strip. 

Bi-Flex Cowl Saver can be adjusted for maximum stiffness across the gap between the engine baffling and the cowl. If you have a large gap, you will want to extend the un-scored portion out closer to the cowl so that the stiff un-scored part of the Bi-Flex Cowl Saver is bridging the gap. The stiff un-scored material will prevent air pressure from blowing the Cowl Saver out of position. If the gap is small between the engine baffling and the cowl surface, reduce the amount of un-scored Bi-Flex Cowl Saver extended across the gap. This will give you maximum flexibility for the best possible seal. After adjusting the Bi-Flex Cowl Saver position for the right amount of un-scored material in the gap, trim away any material extending more than 1/8 inch from under the retainer strips.

It is certified to meet AMS3320G, which is the same industry standard specification to which other fiberglass reinforced silicone baffle seal material is certified, however it is not an STC or FAA-PMA product. It is ultimately the installing mechanics responsibility to determine whether the material is appropriate to repair the baffle seals on a specific aircraft.

McFarlane does have FAA approved die cut baffle seal kits for the re-start Cessna 172 aircraft; please see P/N BSC-KT-1. We developed this first because our patented material solves the firewall crack and other baffle seal related problems on these airplanes. McFarlane will develop more FAA approved baffle seal kits as engineering time permits.

Yes. Cowl Saver is stiffer than most cowl seal material in the un-scored condition. Bi-Flex Cowl Saver can be adjusted to better bridge the gap between the engine baffling and cowl surface. See the question “How much Cowl Saver material goes above and below the rivets?” for more details.

McFarlane recommends the Bi-Flex laser scored Cowl Saver baffle seal material for aircraft that have fairly straight baffling and cowl lines. There is no strip baffling material that works well for sealing a curved cowling. You can cut wedges out in the strip and stretch the outer edges or overlap it, but the best fit for a curved baffling is to cut a curved piece out of a flat sheet. Many customers order both the Bi-Flex roll and a flat sheet to give the best and easiest installation possible. You will then have enough material to do several airplanes.

Please also read Customized Flexibility for Optimal Cooling.

Use of a deep throated hand squeezer will make installation using one hand easier. Always adjust the rivet squeezer for the right rivet height when the squeezer is closed all the way. This gives you maximum squeezer leverage and ease of use.

McFarlane manufactures a patented, Teflon-bonded, reinforced silicone rubber baffle seal material that gives you 30 times less friction on one side. Bi-Flex is our trade name for the laser scoring of this material to give maximum flexibility only where it is needed. For more information, please read Customized Flexibility for Optimal Cooling.

Yes, Bi-Flex costs 25% to 50% more for the extra processing and it will take a little longer to install, but this cost is small compared to the cost of cowling repairs and other damage from the engine movement that is transferred into the cowling and airframe. You will see a drastic reduction in cowling wear, cracks, and fastener fretting. You will also see a lot less cracking and damage to the metal engine baffles.