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Frequently Asked Questions About PML Products

We are happy to answer any questions you have on our products. If you cannot find the information you need on our website, please contact us at (310) 671-4345 or (800) 335-4345 or e-mail

Questions and Answers

How can I get custom engraving?

PML does not offer custom engraving. We recommend contacting Scott at Advanced Auto Graphics in Kansas, 620-562-3563.

Which transmission pan or differential cover will fit my vehicle?

Q: I'm interested in buying a part for my vehicle. I've browsed your website. But I'm still not sure which differential or transmission I have. Can you help me identify the correct one?

A: Usually knowing the year, make, and model will narrow the choices down. Try searching by your vehicle information. See the PML Search By Vehicle Info Part Matching Tool then check your vehicle to see if any of the results match.

When you checking your vehicle, the simplest identifier is the number of bolts holding the pan or cover on. The shape of the perimeter of the part (the gasket surface) is often distinctive and can be compared to the pictures on our website. Some differential covers look like a stop sign, others like an egg laying on it's side. You can use the dimensions of our parts and compare those to your stock part. Sometimes, you can ask the parts or service department at your local car dealership to use your VIN # to identify the transmission or differential in your vehicle.

PML offers more than one pan or cover for some transmission and differentials, which can be confusing. Different vehicles can have different clearance requirements or need different fill or level check holes so PML offers a large selection.

If you email us at a picture of your stock pan or cover, we can point you in the right direction.

What is the difference between the finishes PML offers?

We have a web page about this. Please read: Finishes and Construction of PML Parts.

How much oil do I need?

Q: How much oil do I need to buy when I'm ready to install one of your transmission pans or differential covers?

A: Consult the owners manual (or service manual if you have one) for your vehicle. It should list the amount of oil needed when draining and refilling the transmission or differential. The added capacity beyond stock for each of our parts is listed on the website in the text next to the picture of the part. Add this amount to what your manual says you need for refill with the stock parts.

Some people go to the trouble of collecting all the old oil that was drained out and measuring the volume, then adding our listed additional capacity to it to determine the proper amount to put back in.

When you are finished, always use the procedure prescribed by the manufacturer of your vehicle for checking the oil level. This will be available in your owners manual. On differential covers that came from the factory with a fill plug, our cover will also have a fill plug which should be at the same height.

Why more oil?

Q: What is the benefit of having extra capacity for more oil in my differential cover and transmission pan?

Extra oil provides additional cooling for the transmission and differential under stressful conditions. Heat buildup, the chief nemesis of a transmission, causes the oil to lose its lubricating properties. Break down of the oil leads to increased wear on the clutches, bands, and seals. The end result is costly premature rebuilds and lost time. Our covers and pans feature raised cooling fins in addition to the increased fluid capacity to reduce oil temperatures. Customers have reported temperatures 20 to 30 degrees cooler. Drain plugs are included on all covers and pans to make oil changes easy.

Does a gasket come with my new transmission pan?

Q: When I buy a transmission pan, does it come with a new gasket and filter?

A: No, our transmission pans do not come with a gasket or a filter. We leave it up to each customer to decide what type of gasket they want to use. Often with late model vehicles, the original gasket is a reusable type and no replacement is needed. The gasket surface of our pans is flat and smooth like the majority of original pans and most of the time works well with the OEM gasket.

What you will find in the box with your new transmission pan or differential cover will be a new set of bolts (longer than stock & the round socket head cap screw type), drain plug with sealing washer, and some installation instructions.

Deep pan with a stock filter?

Q: What filter do I use with your deep transmission pan? On GM or some Ford transmissions, the pan actually holds the filter from falling out of the valve body. How can a deeper pan work with the stock filter for these vehicles?

A: Because the floor of our deep pans for these vehicles is further away from the valve body than the stock pan, our deep pans feature fingers that are part of the floor of the pan which rise up to the height of the stock pan and hold the filter. The advantage of this design is that it allows you to have the cooling of additional oil capacity while using the readily available stock filter.

Some have asked whether this arrangement will end up leaving a stagnant layer of oil in the bottom of the pan that does not get used. There is plenty of mixing going on with oil being sucked out by the filter, returned from the oil cooler, and the movement of the vehicle that this is not the case. With most of the larger transmission pans the perimeter of the pan is so big that the floor only needs to be dropped an inch to an inch and a half to gain 4 quarts of additional capacity.

If in the future you find a deeper filter that you want to use, the filter support fingers can easily be ground down to the proper height for your new filter.

Fluid Temperature

Q: I installed one of your pans and my fluid temperature didn't change. What gives?

A: Fluid temperatures depend many variables: vehicle configuration, the driving conditions, weather, the stress on the transmission. It also depends on where the temperature is checked. Some customers report temperature drops only when they are towing or hauling. Many report quicker recovery to lower fluid temperatures also. The average customer reports a 10 to 20 degree drop. However, because of all the variables, there's no guarantee.

Fluid temps that are too low are also bad. If you are in a sub-zero climate, you might need a warmer.

If your temperature was normal before installing a PML pan, it could be similar after because that is the optimum operating temperature and the system will keep the fluid at that normal temp. "Normal" varies with the transmission, but a common range is 160 to 190 degrees.

If your temperature is still too high, verify the fluid levels. Consider adding a transmission cooler. Change your fluid often. Call your mechanic or transmission shop.

Motorhome with a 454

Q: I have got a motorhome with a 454. Do you have a transmission pan for this?

A: If your motorhome is newer than 1990, it should have a 4 speed automatic known as the 4L80E. We recommend our part #9167 early style deep pan for this application. Look carefully at the back of the pan to see if you have clearance for a deeper pan. Often the leading edge of the frame cross member that holds the rear transmission mount sticks far enough forward to make access to the rear bolts on the pan difficult. If this is the case on your vehicle, you will have to remove a semi circular piece of material 2" wide by ½" deep in order for our pan to fit. This modification has been done by many others before you. It works and is relatively easy.

If your motorhome is a 1990 or older, it should have the 3 speed Turbo 400 transmission. We make a deep transmission pan, part number 9683, for this transmission. It is the same depth as the OEM truck pan which is likely on your vehicle. The advantage of our pan over stock would be the drain plug, cooling fins, and resistance to leaking. As with the later motorhomes, look carefully at the rear of the pan and the frame crossmember. If your pan has a beveled edge to clear the frame, our pan will not fit.

Will your pans fit on a 4WD with a 700R4?

Q: I know of people who have had to grind material off of an aftermarket aluminum pan to clear the torque converter cover on 4WD 700R4s. Is this a problem with your pans?

A: We are unaware that this is an issue with our 700R4 transmission pans. Typically if something is not a direct bolt on we hear about it. We have heard about the need in certain applications (not specifically 700R4) to modify the leading edge of frame crossmembers, shift cable brackets, and some aftermarket exhaust pipes to make room for our bigger pans.

Will my 700R4/4L60E shift cable bracket need to be modified?

Q: I have a 700R4 and my shift cable bracket mounts to the pan. How will this work with your pan?

A: On 700R4 & 4L60E transmissions there are several orientations for the shift cable bracket. If your shift cable bracket mounts using 2 of the pan bolts, and hangs down alongside the pan, you will have to modify your bracket. Our pan is approximately .150" thicker than stock and will require some material be removed from the bracket in order to prevent contact with the side of the pan before the bolt holes line up. We have literature that describes in words and pictures how this is done that we will be happy to supply if you need it.

If your shift cable bracket mounts on the transmission case above the pan there will be no modification needed.

What type of drain plug do you supply?

Q: How big is your drain plug? How far does it extend beyond the edge of the pan? There is very little clearance on my Suburban (or whatever).

Magnetic Drain Plug

A: Our drain plug is a standard ½" diameter by 20 threads/inch magnetic type. It is sealed with a copper washer. When installed in one of our pans, the head protrudes 0.400" beyond the edge of the pan.

Our drain plugs are magnetic to catch any bits of metal in the transmission or differential oil.

How big are these transmission pans / differential covers?

Q: I want to add capacity to my transmission or differential but am worried that I will have a clearance issue or that installation will be impossible without removing other parts of my vehicle. Can you provide more information?

A: We provide on this website, the general dimensions, and a 4 view drawing of each part so you can visualize the shape and size of our products. If you have looked at these and you still need additional information, feel free to give us a call.

How do you handle returns?

Q: I'm still not sure whether your product will fit on my vehicle. If I order one of your products and it won't fit or I don't like it can I return it?

A: Our return policy allows for returns or exchanges within 30 days with a 20% restocking fee. After 30 days, no refunds or exchanges are allowed. So if you return the part to us in as new condition, you will be given a credit for the purchase price minus a 20% restocking fee. You will not get a refund for the shipping to you and will have to pay the shipping to get the part back to us. If you modify or damage the part it will not be returnable. All special order sales are final.

I want a custom pan/cover to my specifications. How much would this cost?

Q: I've looked at your products but I need something different. What would you charge to make a new pan or cover to suit my application?

A: If you want something for an application other than what we currently offer, we have to start from scratch. A typical new product requires a $25K investment in design and tooling before the first part is available. If there is enough customer interest to justify this, or a sponsor to help with the design & tooling costs, we can go forward on a new project. Our tooling does not lend itself to building 1 or 2 of something.

If you want a variation on an existing product, this can be less expensive. Call David and provide the details of what you are looking for to get a quote. We have full machining abilities in house so if you need some custom machining done on one of our parts, contact us.

How does PML test the fit of a cover or pan?

Q: How does PML test for form, fit and function?

Valve Cover Prototype
PML Valve Cover Prototype

A: Once we have created a three dimensional (3D) computer model of our new part, this computer file is used by an LOM (Laminated Object Manufacturing) rapid prototyping machine to create a physical model of the new part. Click here to see a picture of an LOM machine. The LOM model is an exact replica of the finished part with the exception that it is made of laminated paper instead of aluminum. The LOM model is then bolted to the cylinder head, transmission, or differential to be sure that it fits correctly and has all the features and appearance that we want.

Once we are satisfied with our design, sand-cast tooling for the new part is created. The first sample aluminum castings from the hard tooling are machined and a finished part is installed on a vehicle. This allows us to be sure that the finished part fits and functions as we intended before more castings are made and machined for sale to customers.

Thick Walls

Q: How do thick walls and gasket flanges make for better parts?

A: PML auto products typically feature walls 5 times as thick as most stock parts (5/32 inch vs. 1/32 inch) and a gasket flange 12 times thicker (3/8 inch vs. 1/32 inch). Stock parts are a thin wall stamped steel construction. They bend, twist, dent, and puncture easily. PML thick wall castings are very stiff and will actually strengthen your transmission case or differential housing.

The gasket flange on thin wall stamped steel parts is very easily deformed. All it takes is a slight over tightening of the mounting screws to bend the flange. Once this happens the part is guaranteed to leak. Our gasket flange is precision machined on a vertical mill to ensure a flat and smooth gasket surface. The thick gasket flange is very stiff and will not deform even if grossly over tightened.

Sand-cast Aluminum

Q: What is sand-cast aluminum?

PML Sand-Casting

Sand-Casting in Process

A: Aluminum is a metal that provides a high strength-to-weight ratio and provides for good heat transfer so our pans are strong and help cool your oil. Sand-casting is the process of pouring of molten metal into a mold to create one thick, solid part.

Sand-casting is a manufacturing technique where a tool (which is the part constructed out of wood or plaster) is sandwiched between two rectangular boxes. Sand is packed into the boxes. Click here to see a picture of a differential cover tool. The result is a big block of special sand with a hollow area inside which looks just like the negative of the part.

Molten aluminum is then poured through passageways in the sand which lead to the hollow area inside the block. The aluminum is allowed to cool and solidify. Once cool, the boxes are removed and the sand is broken away from the aluminum. The result is a raw part which looks just like the finished part but without any of its machined features (mounting holes, gasket flange, drain/fill holes for example).

Sand-casting allows for a one piece part with more complex shapes & features than die casting which reduces the need for machining and welding.

Many other covers and pans are die-cast or stamped. Stamped parts are thin. Also, many believe that sand-cast parts more closely replicate an original, classic look than die-cast or stamped parts.