Semi Syntetic Oil

Hi members,
 
I just had my engine oil changed few days ago.I changed from normal Shell Helix Super to Elf Semi Synthetic 15W 50.I discover that my engine sound abit harsh and noisy.Just wana ask some advices is it suitable to Semi Synthetic Engine oil when previously using normal engine oil?
 
Mitsubishi Lancer GLX 1.5(1994)
 
 

Do you always use 15w-50?  That seems a bit much, I use 10w-30 synthetic in my 90 gsx.

Might be too thick.

Last time I used Shell helix 20W-50.I have heard that Synthetic oils are better so i got it changed and serviced.Anyone tried Shell Semi Synthetic 10W-40 is good for older lancer like mine? 

Why dont you just run 10w-30?  15w-50 and 20w-50 is way too thick.  Diesels use that ****.

Thanks dsm,

I will change to 10W 30 oil at next service, any good recommendations on the Engine Oil?

Mobil 1 always served me very well.

switching from regular oil to a straight synthetic may cause so small leaks to occur because the synthetic is a thinner oil. But a mix is a good idea. On an engine like the lancer though, i havnt heard of the brand of oil being all that sensitive in those cars.

first point....  dont use anything thicker than 5w30 unless specified.
second point... Semi-synthetic is a TOTAL waste of money.  Either use regular oil (which is ALL you need in a 1.5 liter lancer) or fully synthetic.
third point.... synthetic oil is safe to use anytime in any engine unless specified otherwise (as is the case with mazda and their rotary engines).  it will NOT cause leaks.  it will NOT hurt anything.  Synthetic oil is not "magic" oil, made from fairy dust.  It is simply a petrolium product, identical in most ways to normal dino oil.