Conventional vs high mileage oil

[michaelmiller85]

Just curious what the difference is between conventional and the premium oils are, such as the castrol GTX and etc.

[getnpsi]

bobistheoilguy.com too much about oil to read in one session on there.

Check the promotions and rebates area. If you can score synthetics for $3 a quart you've done very well.

High mileage oil tends to not be the latest spec requirements for energy conserving, and they claim to have a higher dose of additives to clean out a less than optimal engine, and seal conditioners to slow leaks. You can use a high mileage oil in a new engine, it doesn't hurt them or anything. They are also synthetic blends which is a slightly better oil, but now the most inexpensive oils are refined much better than they were not long ago, so they are technically blends too anyway.

SN is the latest spec oils are supposed to meet. A 1993 model year car calls for SH so any oil out there except for the 99 cent store is good for it.

[FestYboy]

^ syn-blends are only required to have 10% synthetic oil by volume, so it's not worth the trouble.

[Pu241]

^ syn-blends are only required to have 10% synthetic oil by volume, so it's not worth the trouble.

I had read somewhere it was only 3%.
doesn't mater in any case, if it had been 25% you would still have the non-synthetic molecules breaking down before the synthetic ones.
I don't really see any point to a synthetic blend.

[zoom zoom]

I heard that if you go with synthetic you shouldn't switch back to regular, and it's really bad on your seals if you do, but I don't know how true that is. My theory is that these engines were made for a non synthetic oil, so I would rather use a manufacturer spec oil. You don't put 89 octane fuel in a 50's or 60's model car made for 110, so why use new oil that's not exactly designed to work with older model cars? The new engines/seals are designed for synthetic... as far as conventional and premium blends, price is the only difference I know of..I just get the cheapest 5w30 in the winter and 10w30 in the summer..

[Pu241]

Engine oil is designed to be backwardly compatible with older engines and oil specifications per API. The original "manufacturer spec" for the festiva was 10W-30, later that was changed to 5w-30, so what oil should you use?
Synthetics are superior, if expensive, to non synthetic oils in nearly all the characteristics of a lube oil.

Zoom Zoom, what is the chemical difference between a synthetic oil and regular lube oil?
Asking so you will do some searching and help others learn what the difference is as well.

[TominMO]

I heard that if you go with synthetic you shouldn't switch back to regular, and it's really bad on your seals if you do, but I don't know how true that is.

People I trust tell me that this was true when synthetic oil first came on the market, but they have gotten around that problem since then.

[getnpsi]

Synthetics excel in conditions most regular festiva's will not see... -40 degrees, and 240+ oil temperature. If you have a turbo swap you should use synthetic not for the engine but for its turbo. I regularly use conventional oil in a turbo engine as a top off, no ill effects. Would i do a whole change on it? Probably not.

[kumalaba]

i dont know much about which oi to use(syn or conv) but i put this in my fj & at 4500 miles it still was super clean looking.

[zoom zoom]

chemically, the synthetic is not made with petroleum like regular oil, but made from man-made products like plastic/foam/... which is (insert technical mumbo jumbo blah chemical alklylated polymorpherization heatshrink add carbon radiation) made into a fluid.

regular oil starts to break down immediately with heat, but synthetics aren't as susceptible to breaking down with heat. from what I've seen, it's thinner/slicker than regular oil, which reduces friction..in turn, heat. Synthetics are supposed to reduce carbon and sludge buildup because they don't break down like regular oil.


The more I read up on this stuff the more I am starting to think I should use it, honestly I never really cared enough to make a biased opinion. Using stuff the manufacturer recommends is what I was always taught to do, having worked as an oiler for local 18 operating engineers with cranes a couple years ago, and daily working with 400 hp-1200 hp deisel engines today, you can't just use what you "think" is best in machinery like that, you have to use what the manufacturer recommends, and you don't want to be responsible for deviating from that and someone getting hurt as a result.

As far as a personal vehicle is concerned, do what you think is best.. google has days worth of information on the subject.

topic wasn't really started for synthetic v regular oil, so i'm sorry for goin off topic.

[Pu241]

Zoom Zoom, no apology necessary, you dug up information that made you reconsider what you are doing. I consider that to be time well spent. Hopefully, others now understand more about synthetic vs conventional oils and can make informed decisions about what to use in their engines.

[Bert]

In most regards you get what you pay for. Engine oil sales are a hugely competitive and cost-conscious business.
Bargain basement non-detergent motor oils were available for $1 a gallon 35 years ago (1/4 the price of conventional motor oil) but if you ever made the mistake of switching back to regular oil after using that stuff for awhile the metal particles and engine sludge went right back into solution and very quickly ruined the engine.

I've been running synthetic oils in all of my vehicles for 22 years and one of them (86 F150) now has almost 1/2 million km on the clock and still uses no oil or has ever had the engine serviced. Synthetics do not readily wick off the parts so engine wear upon start up is much reduced and synthetics do not dry out seals and gaskets like regular oil does. The mechanical fuel pump, which is lubricated by engine oil, on the F150 lasted 425,000 km (the mechanic at the time was literally jumping up and down in surprise when he saw that the stamped-steel kicker arm had worn right out and yet the rubber diaphragm was still intact and pliable)!
I figure the money you save in labour and tax expense, by doing oil and filter changes yourself, merit upgrading to better quality oil and filters as a reward.