Yes to Synthetic ?

[naVan]

to much info on internet is making me confuse.i am using Mobil Super 1000x2 10W-40 rite now.just because its mineral based i wanted to switch to synthetic like M1 5W-50 or Super S Plus 10W-40 which is semi-synthetic.

on most of the forums,like 'bobistheoilguy' i read its completely ok to use synthetic in old engine and there are myths too with seal issues using synthetics in old engine.

i run 96' blacktop SR20DET with 155k kms on it,running upto 8k rpm is usuall for me,and it runs great,compression is above 9.

thinking synthetic will provide better protection and engine life,i want to switch to M1 5W-50.but here everyone tells me not to use synthetic in old engine.m all confused.

Please Help.

[KA24JEF]

well for what i understand you can use it but it needs to be a slow prosses like to use a semi first for a few oil changes before you go full on synthetic, and i can see why it wholdent help any motor,

[naVan]

thanks,yes i have been thinking the same.switching from 'Mobil Super XHP Plus 10W-40' or 'Mobil 1000x2 10W-40' to semi synthetic will be wiser.

anyway,if anyone more can help is welcome

P.S and also i want to stick to mobil,cause this is the only reliable brand available in my country ATM.anyway i am thinking to go for 'Mobil Super S Plus 10W-40' for now.

[KA24JEF]

what country you live in? mobil is really good but iv allways been a valvoline guy lol

[Justinians_2:40]

I've done a lot of research on oil and I've yet to find any legitimate reason not to use full synthetic on older engines or not to switch straight to full syn. If you're worried about seals or anything like that, just get some M1 full syn high mileage, it's supposed condition seals. I wouldn't go as high as 50 weight though, I think that's a little too heavy, I usually stick to 40 weight and thats in Florida where it's still 90 degrees in October.

[KA24JEF]

well iv allways been told to switch slowly because it can get a littel smoke ,switching from regular, to synthetic, just like if you have a old motor and you put some sea foam in it to clean it t smokes a litel for a littel wile lol but i do agree that thir is no reason not to

[naVan]

what country you live in? mobil is really good but iv allways been a valvoline guy lol

i am in Pakistan,ambient temps here in summer go as high as 45c+ and in winters its as low as 5c.now a days its 25c-30c.i cant find 15W-50 for the moment,if its mobil1 my choice remains 5W-50,considering multigrade.

[naVan]

I've done a lot of research on oil and I've yet to find any legitimate reason not to use full synthetic on older engines or not to switch straight to full syn. If you're worried about seals or anything like that, just get some M1 full syn high mileage, it's supposed condition seals. I wouldn't go as high as 50 weight though, I think that's a little too heavy, I usually stick to 40 weight and thats in Florida where it's still 90 degrees in October.

i think i should be sticking to semi-syn 10W-40,as i change oil every 1000-1500kms,its like 4 times a year and costs me 42USD including filter change x 4times = 168USD/yr

keeping in mind the motor has 155kms on it,and i drive hard.

[Justinians_2:40]

As far as your oil weight choice, if it gets that hot, I suppose I could see using a 50 weight (we usually stick to a 40 even in our turbocharged Formula SAE car and that seams to be heavy enough for us, even in high heat), but whether it's a 10w or 15w won't matter too much, that's just the weight of the oil when it's really cold, almost right after you start it, it will warm up enough for that not to matter. Also, with that high of heat, synthetic will hold true to it's rated weight much better for much longer. Conventional oils breakdown pretty rapidly at those high temps, both due to the fact that they're conventional and the fact that the additives to make it thinner at low temps, for starting, also have a negative effect on the oil at high temps. Basically, synthetics are much more consistent through out the temp range.

To address KA24JEF's comment about the synthetic oil causing smoke due to cleaning, whatever contaminants are cleaned out of the system will be caught in the oil filter. If you're experiencing smoke, that means the only thing keeping oil out of your combustion chamber was either carbon deposits on your valve seals or carbon deposits on the piston/piston rings. Now that those carbon deposits have been cleaned away, you'll get oil leaking into the combustion chamber, burning up and causing a blue smoke. If this is the case, the problem is not your oil, but the motor itself. Seafoam only smokes when it is ran into the combustion chamber via the intake or fuel, otherwise, if you get smoke or bad compression afterwards, it's for the same reason as the oil.

Sorry for the long post, I was thinking about this in class and just wanted to be able to provide the most info I can.

[KA24JEF]

makes perfect sence to me like i sed iv have only been told that never seen for myself

[amanoma]

is that why im having a bad idle and sometimes im stalling,cuz i used to have a regular oil (i don't know what kind of brand the mechanic put into my car) and i just changed my oil and used full synthetic royal purple,i used to have an automatic ek without tachometer and did the same thing and the car is like almost stall i didnt mind before cuz i dnt know whats goin on.but now i got an s13 im confused if its the iacv vacuum lines or the oil

[Justinians_2:40]

Can't say 100% for sure, but I would definitely check the compression. If compression is low, you'll want to do a leak down test to try to pin point where you're losing compression, if not, check the IACV. The FSM will tell you how to check both. I don't know of any links to show you how to do a leak down test, but I'll try to get something up on my site if you need it, it's pretty simple.

[ward28465]

The only problem you might encounter while switching to synthetic is an oil leak. Syn. oil molecules are all the same size and are smaller then conventional oil molecules thus possibly leading to a oil leak if your engine is not sealed up good. I have an SR and as soon as i got it i put full syn. mobile 1 in it and never had a problem.