Engine oil Castrol or MOTUL

I use Motul in my built engine (not IAG) per the recommendation of the shop that built it.

If it’s actually an IAG long block, they spec Motul 8100 X-CESS 5W-40 (or an equivalent high quality 5W-40 full synthetic) because their bearing clearances are set up for that weight, not the thinner OEM oil.

Motul is a good oil but i stuck with the OEM stuff when i replaced my clutch

I recently switched from the stock Royal Enfield engine oil to Motul 10W40 fully synthetic. The bike feels noticeably smoother and cleaner.

During all my oil changes, I\u2019ve taken a sample and sent off to Blackstone for analysis.\n\nEven after 12k miles, there\u2019s still enough TBN left that I could have continued using it out to 15k miles.\n\nDissolved metals and other elements were still within universal engine norms so it wasn\u2019t like the sample was abnormally contaminated.

I use Castrol EDGE 5W-30 LL Fully Synthetic Engine Oil on my B48 pre LCI G21 no issues at all and complies with BMW specifications

Pero nag stay ako sa motul since 2019.

General rule of thumb for mqb cars is if it\u2019s stock, run stock spec oil. If it\u2019s tuned run 5w40. Personally we run Motul 8100 xcess gen 2 5w40 in 3/4 cars.

For example my previous BMW engine was very noisy with mobile 1, and quiet with castrol

This sub loves to praise motul, but it caused me to foul up my spark plugs and have misfires. I tried both the 5W30 like the manual calls for and 5W40, but shortly after I changed to motul my plugs fouled up. I replaced them, they fouled up and misfired again. I tried it a third time cleaning the MAF sensor, checking if the plugs were torqued okay, checking the seal on the coil packs, etc... still fouled up. I finally guessed it was the motul and did an oil change away from motul and swapped the plugs again. 14k later no fouling.