lets say you just bought a used teg with a b18b and the owner "claims" to have used 89 (or w.e the next one up from 87 is) octane... would it a better idea to "continue" using 89 octane or would going to 87 be fine?

just not sure if the whole oil concept where if the engine hasnt been using synth you shouldnt switch over to it for older cars

 

87 is fine....

 

Just run 87.

As for the synthetic oil. You can switch it up as well. Change the filter with it of course.

 

Running 87 won't hurt the motor, it will save on your pocket of course.

 

its been running synthetic since day one but i was talking about cars that havent been apparently if you start using synth you might get leaks?

 

I honestly switch oils all the time. I dunno what the previous owners were putting into my car. But when I first got it I ran regular oil. I later switched to synthetic oil and it was fine no leaks. They say synthetic is better but who really knows. If you wanna use go again it won't hurt and if you don't engine will be fine. Just do regular maintenance and it will be strong.

 

Ehhh. I get whatever oil is on special at the time. Filter is the only key really. As for which leaks? If you're leaking with synthetic your gaskets are gone in the first place. On my old one it was the valve cover gasket, oil pan, and cam seal. it did leak a bit more, but nothing scary. Just replace the easy ones. I noticed I did get slightly better mileage with synthetic though.

 

meh.. i run 91.. lol

 

The whole gas and oil theory is bs.

Octane difference is how much heat it can take before it detonates. Yes, older engines could use higher octane, because things like carbon build up may cause extra heat but nowhere close to cause a problem with 87.

Oil...switch all you want.

 

^Exactly.

Running anything higher than 87 in a car/engine (unmodified, aka, no turbo/sc/cams/higher compression) that was designed to run on 87 is a complete waste of money and often it will decrease performance and fuel mileage because the engine will not be able to completely burn the higher octane fuel properly.

Higher octane does not = more power.
Higher octane = ability to allow an engine to make more power via major mods, such as cams/higher compression/sc/turbo etc.. (intake/header/exhaust are NOT a major mods...lol).

Basically all you're doing by putting in higher octane is putting in fuel that is more difficult to ignite. This decreases performance and fuel economy. Higher octane requires more heat via higher combustion pressure via higher compression or boost to ignite. It has reduced potential for detonation(pre-ignition). It does not produce more power in any way. It also will not "clean" your engine, in fact it can leave more deposites because it's not being burned properly and completely in an engine designed to run on a lower octane fuel.

There are very very rare cases in older/higher-mileage engines where it's possible for there to be enough carbon build up on the pistons and combustion chamber that it actually slightly increases compression, just enough to cause slight detonation. Again these are extremely rare cases, which I've never seen, only heard about. And if there is that much carbon build up in your engine, you probably have other issues that need to be addressed. But basically, if it calls for 87, just run 87.

Engine oil; Part of the problem why people find they end up with leaks when they switch to synthetic on an older/higher mileage engine is becuase it cleans away a lot of the junk left by conventional oil that was blocking/clogging potential leak points. Also, synthetic, by design, is able to flow through much tighter tolerances (smaller spaces) much more easily. If you do find you have leaks, chances are, something needs to be fixed anyways. You can mix and switch between conventional and synthetic all you want. It doesn't matter. I believe it is a myth ------ by shops that you must stay with synthetic once you change over, to keep you buying synthetic because it's more expensive. I have yet to find any valid reason to why you can't switch. I've done it myself several times with zero issues.

Synthetic resists breakdown and it's flow viscosity remains the same over a much wider temperature range. This means it doesn't go like molasses at -20 degrees and doesn't go like water at extreme high temps. For daily driving, any type of oil is fine. If you're going to use conventional, you'll want to make sure you choose according to the season and oil weight recommended for your engine. With synthetic, you can get away with using the same weight all year round. If you use your car for competition (autocross, drag, time attack etc..) you'll want synthetic because it'll stand up to the abuse WAY better than conventional oil. Either way, make sure you change the oil regularly. It is perfectly safe to go 10-15,000kms between changes with synthetic, but I'd still stick to the ~5000-8000km changes for regular oil, because it just breaks down too quickly to leave it in any longer. Also, especially for older/higher mileage engines, it's good to keep an eye on the oil level every 2 weeks or so, just to make sure it remains topped up.

Sorry for the novel...lol. Got a little carried away with this reply....

 

Wow mike you covered everything bravo. Well said and this should explain alot to people.