98 corola regular oil to synthetic, engine light goes on?

[GuardianArchon]

A few weeks ago, i did my normal oil change, on my 98 corolla 3 speed(4 with overdrive), before i was using regular oil, tried to switch to a semi synthetic just to see what it give, cause i know it has some better properties to it then regular oil, such as being more robust, and everything was good, now after a couple of weeks engine goes on, check my fluid levels no wires disconnected engine sounds the same, everything generally looks good, a day later engine light goes off, im like ok, came back went away the same thing, now it back again but i seems to be missing my oil, i don't have blue smoke on my car, at least not that i can see, and there are no oil spots so unless tis all sludged out, is it possible that its become just a burn due to it being semi synthetic instead of using a full synthetic, comments would be nice, ive been told by someone i shouldn't have put 10 w30 semi sin into my car, i find it wouldnt be a problem since it was also the garage that did it

[Deep Phat Friar]

"Post hoc, ergo propter hoc" fallacy.

As long as you used the proper weight oil, whether it is full synthetic, semi-synthetic, or otherwise, the oil is not to blame.

If your manual says to use 5W-20, but you used 10W-30, then MAYBE that's the problem (but I doubt that). (I think the '98 calls for 5W-30 anyway, and 10W-30 isn't that far off unless you're experiencing very low temperatures in your area.)

[GuardianArchon]

unless im burning, and not realizing it, thats also a possibility hence the low oil level, but i have none of the other signs

[turbo_slug]

i put 10w-30 pennzoil synthetic into my dad's 99 corolla for the first time. the car had 143000km on it and quite a bit of sludge could be seen inside the valve train when peaking through the oil filler cap. the car now has 145,000 km on it and i had to add half a liter of oil to the car. my guess is that the synthetic oil washed away enough sludge that oil is now able to seep past the seals. i originally picked the synthetic oil because i figured that it would wash away the sludge slower than w/ stuff like seafoam.

[GuardianArchon]

well i did burn a little not even 1L over 7000km, but also i ended up checking the spark plugs, 2 were just a little lose, not enough to lose compression or anything just a little oil came out..... but the check engine light comes from my other post, evap system,