any problem changing to synthetic?

[cyrus240sx]

right now my 95 240 has 140k on and i plan to turbo the ka...would there be any adverse effects if started from now on changing the oil with say a 15w-40 synthetic oil?

[MustangManV6]

ok.. this is what I have HEARD. I have heard above 100K miles you shouldnt change from regular to synthetic oil. The reason is that the regular oil has its own kind of protection on the cylinder walls, but when you change to synthetic it breaks down the old oils protection leaving your cylinder walls without proctetion (for a littl while) and this can lead to pre-mature wear.

Someone can come correct me

[navysnail]

also, some minor cracks in seals that form are stoped up with carbon

with synthetic, the powerfull detergents disolve them quickly and small leaks start to come up.

thats just what my friends dad who works for mobil 1 says

[niznos]

Sythetic is just better in every aspect. Some people swear by what 240kid says about the minor leaks staring up, but I have a 1990 and use synth. and no unexpected leaks began. All my leaks were pre-existing, which I've fixed since. Chances are you've got some minor seepage anyway, most of us do.

Mobil 1 makes a 15w-50 that I used to put in my old Supra and it worked great.

[Checkered-Member]

what i would do is use some oil system flush, before putting in syntactic, so that all the traces of the oil are gone and wont mix in with the new, also using heavier weight on older cars is better since the oil is thicker an oil leak is less likely to occur

[navysnail]

well the worst thing that could hapen is that you would have to replace a few seals, id say put the synthetic in you will be fine, its not like it will create a gushing leak or anything like that if it even does leak in the first place, many dont.

[bokinsmowls]

good stuff to know, Im flushing and changing to synthetic when I do my timing kit next weekend

[180fan]

I switched to syn from regular oils without a problem at 145k on my 89. I didn't start using a flush till about 150k, also I added that product by Restore or something to help raise the compression. That stuff was ok for the first couple times, but stopped using it after a while and just kept up with the regular motor flushes.

One thing though, my other buddy Chris recently switched to Mobil 1 and has 130k on his 93 but sprung a leak at his rear cranks seal. So I'd think the leak issue is a case by case basis.

[cyrus240sx]

ok thanx for all your insights.... i think my next oil change is gonna be with mobil 1 15w-50 and if i get a leak then thats just proof that i need a new motor lol

[bokinsmowls]

so 15w-50 is the way to go?

Should quiet valvtrain a bit, right?

[C-Kwik]

ok.. this is what I have HEARD. I have heard above 100K miles you shouldnt change from regular to synthetic oil. The reason is that the regular oil has its own kind of protection on the cylinder walls, but when you change to synthetic it breaks down the old oils protection leaving your cylinder walls without proctetion (for a littl while) and this can lead to pre-mature wear.

Someone can come correct me

I've never heard of any bonding additives in conventional oil that would not be compatible to synthetics. In fact, I would think synthetics would have to meet a requirement of being compatible with older oils. Just like any new oil probably would. I'm sure Fred can be a lot more insightful on this.

But synthetics do tend to have better detergent properties and if there is enough build-up against the seals, the synthetic may clean this away. If any of the build-up was helping to seal, then the synthetic can leak past it. I really do admire synthetic oils though. I always find deposits under the valve covers of motors that use conventional oil when I pull them off. When I pulled off my valve cover, there was absolutely no deposits on the underside of the cover. I've seen the same result on a Honda that got a steady diet of synthetic oil.

[C-Kwik]

so 15w-50 is the way to go?

Should quiet valvtrain a bit, right?

Depends on a lot of factors. I'd probably refrain form using oil weight as a fix for a valvetrain lash adjustment issue. Oil weight should be primarily based on the operating temperatures it will be used in.

[Ceptos]

will you be rebuilding that engine before installing the turbo?

[hotshot240sx]

synthetic oil is bad for your engine after 100k...you will and i qoute will...start to burn oil...run 20-50!

[hotshot240sx]

i use 10-40 high mileage by castrol..works great!

[Structure240sx]

c-kwik what oil are you useing? i've been running 10w-30 penzoil for the past 7k or so. i used synthetic for about 3k before that. i switched when i blew my turbo cuz someone said it might be better. my built motor only has 20k on it. should i swtich back to synthetic?

[bokinsmowls]

Depends on a lot of factors. I'd probably refrain form using oil weight as a fix for a valvetrain lash adjustment issue. Oil weight should be primarily based on the operating temperatures it will be used in.

not trying to "fix" anything. I thought all KAs had somewhat noisy valvetrains. Mine is a bit noisy, should I check adjustment? Now would be a great time to know, tearing it down in 3 days. My motor has 90K on it, no leaks, no burning oil, and Im running 10-40 right now. Seems like not going synthetic, and using 20-50 is the way to go, please help. This topic seems quite controversial

[Checkered-Member]

synthetic oil is bad for your engine after 100k...you will and i qoute will...start to burn oil...run 20-50!

:rolleyes :slap :slap :rolleyes

I don't even know where to start.

but lets try: what makes you think that?

[bokinsmowls]

could someone please confirm whether or not to change to synthetic?also, does the FSM have valve adjustment instructions?

[Chingon]

what confirmation do you need?

[bokinsmowls]

what confirmation do you need?

WHAT?Have you not read the differences in opinions above??????

[Chingon]

yes and I've also read countless other threads....

By the way, I have yet to see any negative comments about synt. above...

[bokinsmowls]

then maybe I misunderstood what they were saying, I dunno. Im changing regardlessGuess this is one of those topics like the sr v. ka crapJust thought there would be a more clear answer

[guyaverage]

I have switched 3 vehicles to Mobil 1 after prolonged use of dino oil, without even so much as an engine flush. A 1984 Accord which my dad bought new, gave to me and switched to synthetic at 220,000 miles, no problems as of 293,000 miles; 1995 Toyota 4Runner, 73,000 miles, no problems at 106,000; My 1993 240, 81,000 miles, no problems at 86,000 miles. I dont claim to be an oil guru, but the recommendations of several 'experts' to not switch to synthetics after long-term dino oil useage has not translated into my personal real-world AT ALL. No leaks, drips, burning, no oil pressure problems, etc.