I am driving a Hyundai IX35(Tucson) 2013-2014 1.6 petrol engine. according to Manual the recommended oil is acea a5/b5 5W-30 shell. however, I am having trouble finding it in shell stations. apparently they don't have it in this region. instead they suggest 5-W30 Acea a3/b4 or a3/b3. is it a good idea to use these alternatives or should i order the one in manual online.
Update: A3/B3-16 (what they sell)
a5/b5-12 or above (what manual recommends)
thanks
About the A5/B5 oil: These fuel economy oils have a reduced shear resistance, therefor increased engine wear. Should the manual allow other types of oils I would use a good A3/B4 oil.
A good indication for a premium engine oil would be the Mercedes "MB 229.50" or the Volkswagen "VW 504/507" specification. Also the "API-SN" mark should be present. The brand (shell/castrol/whatever..) does not decides about the performance, just the price.
You can compare the specifications by this tool: https://online.lubrizol.com/relperftool/pc.html
Just for clarification:
In my book the A5 specification was invented to lower the fuel consumption by lowering the HTHS viscosity. While an engine that demands A5 oil is supposed to handle the less wear protection (by better design) a good oil with high HTHS (if the manual allows it) increases the engine life.
Your case:
It is difficult for me: I personally would put in something different than an A5 oil, but it is against the manual and I do not want to suggest it to you. Perhaps you should just stick with the recommendation from the manual and use an A5 oil. Skip the "Brand X"-part although, that is the least important thing.
Just for reference:
https://oilspecifications.org/acea.php
https://de.wikipedia.org/wiki/Schmieröl#ACEA-Spezifikation
HTHS means "High Temperature High Shear" and is one of the more important factors on engine wear.
A is for gasoline, B for diesel. The number 3 means high performance and/or extended drain. For gasoline, the number 4 is reserved for future use in certain direct injection engines; for diesel, it means it's for direct injection engines. The number 5 combines 3 (and in the case of diesels, 4) with fuel economy.
Based on this, the benefit of following the manufacturer's recommendation is reduced fuel use. Whether the savings outweigh the extra cost of ordering the correct oil online is a good question, depending on the shipping costs. Answering it would also require more information than what the specifications give. But I believe the main fuel efficiency factor is the weight of the oil which in your case is 5W-30 and you should follow the manufacturer's recommendation with respect to the weight.
