Standard oil vs. synthetic?

Discussion in 'Bad Dog Cafe' started by davo8411, May 22, 2019.

  1. imwjl

    imwjl Poster Extraordinaire

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    I had more waiting for car service than I wanted in the past month. I heard the service writers repeat to customers that all modern engines they service and sell - 4 - require synthetic now.

    Getting all service done by the dealer during warranty has paid for me when issues have popped up later. The dealers seem much better and more competitive these days. I have a Subaru, my wife a Toyota. These days an oil change includes a sincerely decent job of checking the whole vehicle and getting the inside and outside cleaned so I don't consider the dealer a rip off.

    Even decades ago when I was involved with fleet service and machines our trials with synthetic oil were positive - better in cold, longer engine life. The modern requirement is no mystery to me considering the longevity and performance of modern vehicles. Just look at the output of engines in common modern vehicles. Precision and high performance lubricants are part of it.
     
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  2. Ricky D.

    Ricky D. Poster Extraordinaire

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    All the discussion about oil change intervals and oil and filter selection is just shade tree BS if it's not backed up by used oil analysis. There's just no way to know if your oil change intervals are too long, too short, or just right.

    https://www.blackstone-labs.com/engine-types/gasoline/#
     
  3. Dacious

    Dacious Poster Extraordinaire

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    Standard grade fuel is catspiss. I can assure you my LS1 V8 gets about 1km/litre
    Actually the OC monitor is fairly reliable even the algorithm type. The direct condition monitors that measure contaminants by conductivity, soot, viscosity and water are even better.

    A country driven high average speed car might go double the service interval without killing it's oil. A hard driven car with lots of short trip city stop-start might need changing sooner than mileage suggests. Synthetic oil with lower age-related degradation and lower dilution live for a long time.in low mileage vehicles.
     
  4. Blrfl

    Blrfl Tele-Holic

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    That they do. The auto manufacturers do gobs of testing during R&D to come up with their recommended change interval, and even those are conservative. The 3,000-mile interval hails from a time when the engineering, manufacturing and oil were pretty awful compared to what they are today.

    Changing it more frequently than necessary is going to tug at your wallet, but what you dump in the recycling tank will marginally improve the quality of the oil being fed to your local school bus fleet. :)

    5W-40 is a multi-viscosity oil. The number on the left is the viscosity when the oil is very cold, which is when you want it to thin out and flow so it reaches the engine. 5W is good down to -20°F ambient temperatures. The number on the right is its viscosity at operating temperature, and your engine will reach that in short order.

    Multi-vis oils are the reason we no longer have to change the oil when the seasons change.
     
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  5. Ricky D.

    Ricky D. Poster Extraordinaire

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    5W-40 oil is 5W with additives that make it behave like 40 weight at operating temperature. Those additives break down in normal use, and eventually the oil will behave like 5W at all temperatures.
     
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  6. beninma

    beninma Friend of Leo's Silver Supporter

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    Yah the thing with all the oil testing is the guys who designed the motor in your car had testing equipment that is much better than the guy who writes a web page who second guesses them.

    They've got a pile of highly educated engineers who specialized in engine development, they do it full time and they have a huge budget and they did tons and tons of testing of the engine to figure out the best oil for that engine and the best oil change regime for that engine. A lot of them have experience with race cars and such that really stress this stuff. They are also thinking hard about the environmental impact of the service schedule since they're making millions of cars.

    My previous car was an Acura RSX Type-S, the Redline was around 8000rpm. It did not need fully synthetic oil to operate well and Honda did not specify that it needed it, it was specified to use a semi-synthetic for some reason, and it was a weight which had almost no viscosity even at room temp, it poured like water. (A blend?) I had several motorcycles with Redlines north of 12,000RPM that were tuned to the 125-150hp/liter range and none of them needed or specified synthetic oil. These are very highly stressed motors. Because so many motorcyclists would be the type to go buy synthetic anyway Honda specified which synthetic to use if you were going to do so. I did so on one of them, it probably just cost me more money, but I was doing my own maintenance which made up for the difference. All of these engines were ridiculously reliable in my personal experience & in wider stats you see out in magazines/web pages/consumer reports type stuff. They didn't need any help.

    All the engines burn oil, another item that increases oil burn on modern engines especially high RPM ones is the crankcase ventilation system.. a lot of these engines evacuate the air from the crankcase as they run for some reason and they suck up some oil vapor. They pass that back to the intake where the oil vapor would then get burned in the combustion chamber. It's just a question of whether they burn enough for the light to come on before the consumer notices since barely anyone checks their oil anymore.

    I have a Subaru now, it does specify a very light weight synthetic. The oil change interval is 7500 mile. Subaru screwed up a little here, and it will sometimes burn 1qt before 7500 miles. It's harmless. I forget exactly what the mechanic said to me but it sounds like it'd have to burn 2-3 quarts before anything bad could happen, so you'd have to ignore the light for thousands and thousands of miles. Sometimes, but not every time, I need to add a quart before the car goes in for service. Within a year or two Subaru reduced the oil change interval to "fix" this so people wouldn't occasionally see the light come on and have to add oil. The newer ones have a 6000 mile change interval or something and the owners of those cars probably never see the light come on.
     
    Last edited: May 23, 2019
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  7. omahaaudio

    omahaaudio Friend of Leo's

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    Luckily all of the cars that I've owned ran just fine on cat's piss, including a glorious Acura TL that ran on cat's piss, doing an indicated 140 MPH at one point, and getting a day-to-day 36 MPG.
     
  8. fendrguitplayr

    fendrguitplayr Poster Extraordinaire

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    I use regular oil and change it every 3,000 miles. 2007 Chevy Malibu with 78k miles.
     
  9. beninma

    beninma Friend of Leo's Silver Supporter

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    If you follow much motorsports (I don't these days but used to) you'll also see some strong evidence the guys/girls at the car company who set the specs for the cars really have an extra special set of knowledge and do know best.

    It doesn't really apply to NASCAR, F1, Indy car, etc.. where the motors have almost nothing in common with your street motors, but if you watch something like AMA motorcycling or certain classes of sports car competition.. you'll see a given car company will have a factory team and then private teams they sell motors too.

    The factor motors even with the same set of rules always seem to have a big advantage over the privateers in performance and yet at the same time break down less.

    Can't really remember the specifics but I remember 10 years ago Suzuki crushing everyone in AMA Superbike.. the race bike was based on a street bike. The street motor might have been 130hp. The shade tree race guys might be able to run it at 140hp but have reliability issues. The big money privateers might have been running it at 160hp and break down less. The Suzuki factory team is meanwhile running 200hp out of the same motor.. crushing everyone, and never having an engine breakdown all season. (Didn't hurt they had the best rider too.) . This was subtle stuff since all the teams had to follow the same rules.

    I used to hang out in the pits for amateur motorcycle racing and see some of this stuff first hand.
     
  10. Dacious

    Dacious Poster Extraordinaire

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    You wouldn't want to look inside the head or valves after 100,000 miles. The buildup would be horrible.

    I ran my car on standard fuel (91 here in Oz similar I think to your standard 85/86) for two years on lease. When I bought it off lease I ran on 95 for a couple years - it was throwing codes on the O2 sensors.

    I swapped to 98 last few years because I don't so many miles. It's dropped 1.5l/100km or about 2 USmpg. Because the knock sensor allows the engine to run more advance. My 3600lb 5.7 litre V8 does right on 8L/100km which is bang on 30USmpg cruising on the legal limit. That's verified by fill, not off the DIC.

    It's done 140,000km or about 90,000 miles in 15 years, it's on original plugs, O2 sensors and cats. Fires on a flick of the key hot or cold.

    As I plan to keep it, it's getting Penrite full synth oil, good fuel including cleaners and frequent filter changes. The exhaust is light grey even around town. It'll light the tyres for 100feet off the line if you want, easy.
     
  11. memorex

    memorex Friend of Leo's

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    My own experience is that the engine actually sounds better and runs smoother on synthetic oil. I've been told by some mechanics that it's a waste of money unless you buy the synthetic or high milage rated oil filters, because even though synthetic oil doesn't break down like regular oil, it gets dirty and forms acid just as quickly unless you use the better rated filters. And the synthetic rated filters only cost about $10, so it's worth it if you want your oil to last twice as long.
     
  12. schmee

    schmee Poster Extraordinaire

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    ie; Burning oil: I often run over too many miles before having the oil changed in my band van. (Dodge Caravan, 105k miles on it) This time it was 5k-6k miles since last change. No oil gone after 5k miles, none added.
     
  13. boris bubbanov

    boris bubbanov Telefied Ad Free Member

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    Sorry to hear that your gasoline is so bad down there.

    There's been huge improvements in motor fuel in the USA in my lifetime. I worked at a shop that sold automatic transmission parts, plus we restored cylinder heads and welded new rings on flywheels on the side. The amount of buildup in 1978 inside those heads was massive and when I see cylinder heads laying around in parts yards these days I don't see those deposits anymore, or just the slightest amounts. I'd like to tell you what I found when I tore down a head recently, but instead of re-doing them every 30,000 miles (50s cars) I find myself not having to do them whatsoever. But I often know the history behind the dismantled motors I see at my friend's wrecking yard and these "horrible" deposits you're talking about, may exist outside the USA but they tend not to exist here. It may help that people use the better sourced regular gasolines, with good fuel filters and only sensible additives added to the fuel tank.
     
  14. boris bubbanov

    boris bubbanov Telefied Ad Free Member

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    I apologize. I'm an avid reader of other people's posts and tend to have a decent memory and so I assume others are much the same.

    Anyway, I still insist that common parlance is an engine "uses oil" when the level is down and people are actually adding motor oil between service intervals. I've never met anyone who used the term to refer to the incidental, unavoidable losses that are offset by other materials making up the displacement one reads when you pull the dip stick. For example if I told Joe his car had "used" a half pint of oil I am saying we're going to put a fresh half pint of motor oil in there - if there's a half pint of something besides oil in that crankcase and I add that fresh half pint, now I am overfilled.

    But I do wanna back up a little in one regard. Some motors hold volatiles from oil breakdown or from fuel or coolant that got in there by mistake, and their impaired PCV systems don't get rid of these vapors and that's actually a pretty bad thing. Those contaminants IMO play a major role in the breakdown of motor oil and its "rightful" additives and lead to coking and sludge and those are bad. Personally I wouldn't mind having to add some oil now and again, as opposed to believing I had 4 quarts of pristine oil in there when in fact I had 10% or more god awful rubbish in there. So, there are things worse than a car that uses up or leaks a bit of oil.

    I'm looking at the oil in my 2006 Saab 9-5 and frankly I don't like what I see. I don't think my PCV system is working well enough. I'll be taking that system apart, cleaning it and replacing anything I don't like. The irony is that Saab felt in 2006 that they finally had their PCV system working properly on these 9-5s. Prior to that Saab, like Toyota, had some coking issues where people drove ultra short errand trips, very cold temperature use.
     
    Last edited: May 23, 2019
  15. Urshurak776

    Urshurak776 Tele-Holic

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    I have belonged to BITOG since 2003. As others have mentioned, what does your manual say? Follow that recommendation. When warranty period is over, some people move to synthetic to extend the oil drain intervals. Currently, some manufacturers already say 10,000 miles.

    My opinion, after countless oil analysis reports, is if you are running a turbo, or a DI engine, use synthetic as it won't change viscosity as easily throughout the course of the oil change.

    Also, pretty much ANY SN spec oil will do 5,000 mile oil changes, even conventional oil. Oil today is very robust, even the cheap stuff.
     
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  16. boris bubbanov

    boris bubbanov Telefied Ad Free Member

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    Are you suggesting to us that you've seen oil analysis done, where the 5W40 has routinely broken down to straight 5 weight? I think that's more in the nature of an Ultimate outcome. I think in the real world, what you see is impairment of the range of viscosity, not utter loss of range.
     
  17. David Barnett

    David Barnett Doctor of Teleocity

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    That's also a car that was last produced for the 2006 model year. (I was car shopping in 2007 and pissed that the RSX-S was no longer available) Things have moved since that car was introduced in 2001, it's almost a 20 year old design now. A car made for the same market segment today would likely have been designed for full synthetic.
     
  18. beninma

    beninma Friend of Leo's Silver Supporter

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    Hard to say.. those engines along with the S2000 engine were no slouches compared to a lot of current engines, they were very advanced. I think more what happened is the market moved onto wanting turbos, wanting bigger heavier cars, not wanting cars at all and wanting all SUVs and Trucks, etc..

    The Engine in the RSX-S was in the Civic Si for quite a while longer.. it didn't disappear for quite a while till they switched over to turbos or something.

    I would be curious why everything is moving toward synthetic.. it is more likely just to reduce oil waste since synthetic lasts so long.

    There is no correlation with engine performance or fuel economy as far as I can tell.
     
  19. David Barnett

    David Barnett Doctor of Teleocity

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    Perhaps there's a correlation with warranty claims?
     
  20. Blrfl

    Blrfl Tele-Holic

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    "Eventually" meaning "after the end of the oil's normal service life." Engine manufacturers take degradation of the oil into account when coming up with the change interval.
     
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