Synthetic vs Conventional motor oil question

Discussion in 'The Garage' started by leeland, Oct 1, 2010.

  1. leeland

    leeland Diamond Member

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    OK I just got back from the local Auto Zone and the oil I always get isn't stocked anymore

    Mobile extended 5000 mile stuff 5w-20

    SO...I am taken back because I have used it for as long as I can remember and I had to pick a new oil...

    I asked an attendant about some of them...and he turns to me and mentions Synthetic (which is obviously more expensive)...

    I considered it since it is getting closer to winter and it would be easier on the engine starting in cold weather....

    We talk a little more and he says...if you switch to Synthetic...you have to stick to it forever otherwise it does something to the engine (basically makes the engine leak oil) if I were to switch back to conventional at some point...

    Something to do with the molecular make up of the oil...

    Does that sounds right? I have not a clue with oil comparisons...
     
  2. thescreensavers

    thescreensavers Diamond Member

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    You can switch between the two when ever...

    Castol GTX is great oil and its not too expensive.
     
  3. punjabiplaya

    punjabiplaya Diamond Member

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    /top gear
    great for cooking too apparently
     
  4. thescreensavers

    thescreensavers Diamond Member

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    :D
     
  5. mwmorph

    mwmorph Diamond Member

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    Most of the top line synthetic oils are very close. You can feel confident going with
    German Castrol Synthetic
    Pennzoil Platinum
    Valvoline Synpower
    Mobil 1 Extended Life (15k mile)
    and surprisingly Supertech Synthetic (Wal Mart brand, made by Shell)

    You can switch between Synthetic and Conventional whenever, Synthetic can leak a bit more on older cars around tired, worn out seals, but its not too big a deal.
     
  6. Eli

    Eli Super Moderator<br>Elite Member
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    This.
     
  7. WhoBeDaPlaya

    WhoBeDaPlaya Diamond Member

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    There's Pennzoil Ultra as well, which is supposed to be even better than the venerable Platinum.
    I just (~1.5 months ago) switched over to it from M1 5W20 synth and will be doing a UOA on my next oil change.
     
  8. Bartman39

    Bartman39 Super Moderator<br>Elite Member<br>For Sale/Trade<
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    My take on it is no should not be an issue switching back but what I have always understood is more important to stay with the same weight of oil (10-30wt, 5-20wt and such) I run Royal Purple 15-40wt in my Duramax with service interval at 10K miles and do oil analysis each change with no issues and I dont hammer it all the time but it doesnt complain when I do... :thumbsup:

    But note that early steel and cast iron ringed engines did start to use oil if switched back and forth... Not a lot but did see it first hand but all newer engines use moly or chrome type rings are not affected (note the crosshatch procedure or should say honing procedure is different as well)... Only issue is the leaking as mentioned and thats is more with older engines that have been using conventional oil and switched to synthetics as they tend to clean the the varnish build up on seals and even soften gaskets...
     
    #8 Bartman39, Oct 2, 2010
    Last edited: Oct 2, 2010
  9. Gibson486

    Gibson486 Lifer

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    Anyone ever try NAPA synthetic? it's 3.29 a bottle...
     
  10. HarryLui

    HarryLui Golden Member

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    Most people don't know what the different is with synthetic and conventional.

    Most people don't need synthetic oil either.
     
  11. WhoBeDaPlaya

    WhoBeDaPlaya Diamond Member

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    Best bet would be to check BITOG. Someone there has probably done a UOA on it.
     
  12. Bartman39

    Bartman39 Super Moderator<br>Elite Member<br>For Sale/Trade<
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    NAPA synthetic is made by Valvoline... Same stuff but is a kinda older formula but for the price a good product...
     
  13. Vette73

    Vette73 Lifer

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    Pretty much any name brand oil will go a good 5000miles in most cars and most syns can do 10k+ as well. Check owners manual and many now say 7500miles on regular oil is fine.
    Now if you have a turbo, tow a lot of heavy weight, air cooled, etc... then syn oil with a little sooner change will work better.

    I buy what ever name brand is cheapest and meets the specs of the car/truck I am working on. Never had any engine fail due to the name brand oil used. I have broken down hundreds of motors. Only time oil caused an issue is when it had about 30k on it and was more solid then liquid.
     
  14. leeland

    leeland Diamond Member

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    I have always used the correct Oil weight in my vehicles and used Bosch filters (which I feel comfortable with)...

    In the past on an older Civic I had used Synthetic oil in the winter and it worked out well with starting and in general.

    I always try to do my own oil changes as I personally don't trust the quick lube places and am too damn cheap to take it to the dealer for a change.

    Is it safe to assume that either (A) this attendant was just a dumb ass and didn't know what he was talking about or (B) he was just trying to jack up sales?

    Is it feasible to assume that in cold weather that a synthetic motor oil will perform better in cold weather with starting?

    Also, does synthetic oil last longer than conventional oil? On our Honda Mini Van it has an 'oil' sensor that gives a percentage on the oil and indicates when it should be changed.

    The manual states something every 10,000 miles or 6 months but I always go by that gauge...which obviously is variable.

    Thanks,
    Lee
     
  15. CraigRT

    CraigRT Lifer

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    It's great. Ashland product. Think Valvoline. Also great.
     
  16. Vette73

    Vette73 Lifer

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    I vote A as I doubt he gets paid anymore if you buy syn vs regular.

    Syn can last longer if the car is in good running condition. If it over heats, leaks a lot, etc... then the oil probable need to be chaged early as the oil might not break down but there could be a lot of "trash" in it.
    Example I do 10k (give or take) on my CTS and Corvette. My truck gets regular oil and that is 5000miles or every year.

    Syn can flow better at very cold temps. But so does regular 5w30 oil. Now if you live in the North or Canada where temps get very cold then the differance would be enough to warrant using syn. But I live in VA and use regular in my truck and have no issues.
     
  17. smitbret

    smitbret Diamond Member

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    You can safely switch from conventional to synthetic at any time. However, when going from conventional to synthetic, you may get some oil consumption and burning because as an engine ages, micro grooves form on your cylinder walls. Conventional motor oil will fill those grooves and maintain a tight seal. When you switch to a slicker synthetic with more advanced detergents, those grooves get cleaned out and you're left with a (performance-wise) harmless amount of oil consumption. I often switch my cars over to a synthetic after about 80,000 miles and have had no trouble at all. The intervals for oil changes with synthetic are about 2.5 times as long.

    I also switch to a lighter weight oil in the winter, cuz it flows better and quicker especially during a cold start. Heavier weights are better in the summer because contaminants like dust are held in suspension better by a heavier oil.

    Moving back and forth between weights, types and brands is fine so long as you are changing the oil and filter when you do it. You may get some smoke initially, but it is normal and will not harm your car.
     
  18. skyking

    skyking Lifer

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    Not a synthetic fan myself. I prefer new oil more often for the dollar but that is an opinion and you know about those.
     
  19. Meghan54

    Meghan54 Diamond Member

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    Our '02 Blazer, with 214K miles on it, has had syn almost exclusively since its initial oil change at 500 miles. (Started with Mobil 1, also Pennzoil Plat, and the last couple of years, Royal Purple.)

    Has it prolonged its life? Maybe, maybe not....but I think it did help with a situation I faced a few months ago.

    Our aforementioned Blazer had been running slightly hotter lately with poorer gas mileage. Figured was maybe the coolant leak, very minor, from the intake manifold---a common problem that's rather easily dealt with.

    So, went to ATL to pick up a boat. Just after picking up the boat and hitting the interstate, the truck began exhibiting the inability to run beyond 1500 rpm's......any more then it'd act like it was choking down. Began to run a LOT hotter....over 220F. Check engine light also came on......found out later it was the MAF sensor saying low air flow.

    What was supposed to be 3.5 hour drive turned into 12 hours. Guess I should have gotten a tow, but the cost of a flatbed truck for over 3 hours and 300 miles.....hated to think of that! So, I nursed it along all evening and night.

    At one stop to let it cool and just to give myself a break, checked the oil. When I pulled the dipstick, I saw smoke coming from the dipstick tube. Not exactly good.

    Turns out the cats were almost completely plugged....nothing that an $800 repair couldn't take care of. ;) But I do credit the RP oil for keeping itself together and now a couple of months after the fact, the engine is no worse for the ordeal.

    True, an extreme example, but in this instance, it did its job. If it'd been a crankcase of dino oil during this, hate to think what would have happened.
     
  20. BUTCH1

    BUTCH1 Lifer

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    If it's the same intake manifold problem that GM had with some of their V6's it's not exactly minor, expect to pay $500-700 for it to be replaced and some caused coolant to leak into the engine ruining them. Fel-pro makes a replacement gasket that solves the issue if your gonna do it yourself..
     
  21. soccerballtux

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    I notice a huge difference in performance changing at 3k. No way I'm changing at 5k.
     
  22. CraigRT

    CraigRT Lifer

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    There is a recent oil analysis on the BITOG site of a 3.5L Impala running 11.5K miles on Pennzoil conventional, and it looked perfectly fine.

    Oil is not what it used to be!
     
  23. WackyDan

    WackyDan Diamond Member

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    I think what most are missing here... is what is the age of the car you are driving?

    Synthetic oils are noted for not playing as nice with older motors... Kinda like the whole ethanol use in older motors. The gaskets and such were not made with synthetic in mind. Now, I'm sure some of the newer synthetics are formulated for use with older motors...But it your car is ten years old, I'd stick with conventional. If your car is brand new, by all means use full synthetic.

    I have a 98 Dakota... I will never run synthetic in it. Have had it since new, and it is not worth having major gasket issues by switching.

    Wife has an 05 malibu. Could probably switch to Synthetic, but for her driving, probably not worth the added cost. ( I buy name brand by the gallon on sale anyway. ).

    So... I think the most glaring thing you omitted here was the year of your vehicle.
     
  24. Vette73

    Vette73 Lifer

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    No you don;t, at least not any REAL differance.


    If you put your car on a dyno with oil that has 5000miles and then change it to new I bet there be no differance.
     
  25. LTC8K6

    LTC8K6 Lifer

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    You 1998 Dakota should be fine with synthetic oil though. It was popular by then, iirc.