Piston Slap: The Cat's Meow for OEM or Aftermarket Parts?

Sajeev Mehta
by Sajeev Mehta

John writes:

I recently had a local shop confirm the need for O2 sensors in my Jaguar S-Type. With 97,000 miles on them, it seems very likely they need replacement, and the mechanic wants to install factory sensors at the cost of some $650 for the parts. I can purchase Denso or Bosch from the local parts store for less than $200. As these parts were originally designed to last at least 80,000 miles (Federal warranty requirement), I figure that replacements from any reputable source will last quite a long time.

What is your opinion as to brand specific parts versus more generic replacement parts?

I suspect the original supplier was actually Bosch anyway so in my mind they are the same.

Sajeev answers:

Your last sentence is my usual go-to statement, especially as cars depreciate to the age of any Jaguar S-Type. I still remember cringing when my trusted mechanic, some 15+ years ago, said my father’s Mark VIII’s (not the one I currently own) intermittent fuel smell was from leaky injectors. The replacement injectors cost $800, and they were a unique part number with no aftermarket alternative.

Perhaps that’s what he thought since it was the first Ford with that particular engine, but it was all bullshit: all Fords with that engine use the same 24 lb-hr injectors. I grabbed my Ford Motorsport catalog and ordered a set for $275-ish, delivered to the shop, and crossed my fingers for a seamless install. Thank goodness I was right.

Back to the “value” of factory vs. aftermarket parts on a heavily depreciated motor: it really depends. Factory body parts? Yes. In this case? No, get Bosch O2 sensors and pocket the extra cash.

Forget about the price, odds are they are the original equipment manufacturer (OEM) anyway. Sometimes you’ll even get a factory part when buying the “aftermarket” brand: happened to me when purchasing TRW control arms and several HVAC parts. And it’s nice to see those factory castings, part numbers or packaging when you’d never pay for them. It’s kinda like poppin’ tags, sort of.

When do you buy OEM bits, Best and Brightest?

[Image: Jaguar]

Send your queries to sajeev@thetruthaboutcars.com. Spare no details and ask for a speedy resolution if you’re in a hurry…but be realistic, and use your make/model specific forums instead of TTAC for more timely advice.

Sajeev Mehta
Sajeev Mehta

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  • Kyree Kyree on Mar 22, 2016

    Plus, it's Bosch. It's not some no-name outfit you've never heard of (which, itself, probably wouldn't be the end of the world). Buy them.

    • Jagboi Jagboi on Mar 22, 2016

      Never had a problem with NTK, I have with Bosch.

  • Gearhead77 Gearhead77 on Mar 22, 2016

    My Mazda 5 had quite a few suspension issues early on. I replaced all the Mazda stuff that had issues with non OEM stuff. No problems in the 25k since most of the work done, on PA's awful roads with mostly city driving. I've found that every so often, the OEM stuff is the best bet. The rear wiper on the Mazda 5 is a Mazda only part, all the aftermarket blades don't work well, leaving a large area uncleared. It's worth the $20 every two years for the properly functioning part.

  • Vid169489471 The technology exists today to produce a variable color temperature (kelvin) LED lamp. It can vary from 2700k that soft orange look to 6500k the bright daylight with the bluish tint.Since everything in a late model car is computer controlled, it would be an easy task to write a few lines of code that enables your vehicle to not only dim down from hi to low beam but to shift color temp down to the 2700k range for oncoming traffic, then back up to 5000k once oncoming traffic has passed. For the operator it would be automatic and seamless. For older cars they could be retrofitted with LEDs that are 2700k on low beam and 5000k on hi beam. As far as standards, there could be a lumens max, and a minimum. Several States already have minimum lumen standards going back to the old incandescent bulbs. Why not update these to national standards.
  • Jam169859557 More regulation is needed for ALL vehicle lighting systems. [list=1][*]The lighting that is most blinding are the rapidly flashing red, blue and amber lights on emergency vehicles. The lights themselves are blinding, flashing so rapidly that it's impossible for even the sharpest eyes to adjust. What's worse, is the nature of the emergency requires a careful view of the area surrounding the emergency vehicle. There is something going on that needs to be seen. More flashing lights is not the solution.[/*][*]Brighter headlights need to be regulated. The tall riding vehicles do not need headlights positioned so high that they blind drivers in lower riding vehicles. And those heasdlights need to be aimed properly. When I first started driving my 2020 Subaru Outback, many drivers would flash their lights, hoping I would dim my lights. This stopped after I performed am easy adjustment that tilted the beam lower. Late model Subaru headlamps are designed with a sharp cutoff that project less glare above the hood line. When the headlights are properly aimed, other drivers are not blinded by the beam.[/*][*]Customized light assemblies make it more difficult to see the marker lights (tail lamps, turn signals and side marker lamps) that have been tinted. There are many municiple codes that prohibit this tinting, but these laws are seldom enforced.[/*][/list=1]Solutions: Tight controls on emergency vehicle lighting. In trying to make these vehicles more visible, a dangerous side effect is reducing the ability of drivers to see the surrounding perils.Headlight design regulations that reduce the height of the headlight assemblies. Just because a pickup truck has a hood that sits 4 feet abouve the pavement, it does not mean the headlights need to be so high. Owneres should maintain proper adjustments to their vehicle headlights.Establish and enforce regulation requiring a illumination standard be followed.
  • Stl170698708 as someone who hates big government, and their interference;but you can add me to the list of people that are blinded by the lights.unfortunately "the poop is out of the horse and no way is it going back in"They have had 5 years to make lights bigger, badder and brighter because in the vehicle work it is go big or go home!Trucks are the worst because so many people use them to express their dominance and that is big, big, big $$ both at the Original Purchase and in the Aftermarket world.If, we are so lucky to get some good government regulation on this it will also take some very good Court enforcement to get the aftermarket people with fines and lawsuits.Much like the EPA did with the Diesel Tuner Industry that felt emission regulations didn't apply to them.This is from someone that owns said pickup truck with the same bright headlights,but i only use the truck when I have too and always turn off the Fog lights when driving in traffic.
  • Art65765977 I saw a porsche 911 with the most amazing headlights from behind approaching the Sunshine skyway in Florida. The pattern was 108 degrees across sweeping the road like a broom. My brother and I were amazed. I don't know what it looked like from the front but i am sure it was better than American cars
  • Master Baiter This is what happens when you take a chance on a startup auto company. Designing and building cars is hard.
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