2 Engines, each with 500k miles. Difference? The oil: one synthetic, one conventional

[Riverdog]

TBF, some clever (and repetitive) marketing from Jiffy Lube back in the day convinced most folks that 3000 miles/3 months was the "right" change interval. Reality is that even with dino juice, 5k was perfectly fine for the majority of non-extreme use cases and 3K was wasteful, especially since the manufacturers recommended longer intervals. Jiffy Lube was sued multiple times over that.

True, and for modern engineered vehicles perhaps that's fine. But working on older harleys for example, if you have metal shavings on the magnetic drain plug....changing your oil more often is important. I don't believe that the synthetics are magical like their commercials where they encapsulate debris and save your engine. I think metal debris should be removed asap. I've never heard of it hurting an engine to change the oil too often, but the opposite is more likely. But manufacturing has a lot to do with these issues too. My 1960 Harley side cases didn't match and leaked from the factory, the dealer's solution was to use extra gaskets to slow down the leaks. Meanwhile my honda cases were machined so well you could skip the gasket and it wouldn't leak. My BMW motorcycle gets synthetic oil, high octane fuel etc..... but my deuce and 1/2 gets whatever's in my garage. I guess I would support 10k oil changes IF they swapped the oil filter out at a higher frequency.

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[firemedic2714]

Ever since flat tappet cams went away in production engines, we don't really need conventional oil anymore. We don't need the zinc and other additives that made conventional oil so good for what it did. Youtube vids and internet opinions don't matter - conventional oil was amazing for it's day and the engine's of it's day. Do we need it now? Nah. Not because the oil is the problem, but because engines are the problem.

I partially disagree. Only partially because there are antique cars out there (and in my garage) that NEED zinc-fortified conventional motor oil and at a reasonable cost because we're not all independently wealthy. Some of us are blue collar. Engines built after a certain date (probably about the time synthetic oil was really gaining popularity) benefit greatly from Mobil1 and it's counterparts. I use nothing but synthetic in my fleet (where appropriate).

 

[BourbonRunner]

@Riverdog --

Ah, old Harleys and motos in general are a horse of a different feather, especially when you're talking air vs water cooled. IIRC the rule was a reduction of 1/3 the interval if it was air cooled, car or moto didn't matter because the oil is doing all the work of dissipating heat and breaks down much, much faster.

That deuce can run on anything from fryer grease to hair spray. Hell, you could dump your used oil from your Harley in it and it wouldn't care.

Other side of that coin: Our 200k+ 2013 Subaru gets a filter change every 3-4 months and topped off every 1500 with Costco synthetic because it burns it like a champ. I still do a full crankcase change annually regardless of mileage.

 

[Greg_L]

I partially disagree. Only partially because there are antique cars out there (and in my garage) that NEED zinc-fortified conventional motor oil and at a reasonable cost because we're not all independently wealthy. Some of us are blue collar. Engines built after a certain date (probably about the time synthetic oil was really gaining popularity) benefit greatly from Mobil1 and it's counterparts. I use nothing but synthetic in my fleet (where appropriate).

I totally agree...and so does my 1964 GTO in my own garage.

I was talking about modern production engines.

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