5w30 or 5w40 (or 0w30) Castrol Edge Euro vs 0w40 euro edge to reduce engine oil consumption in e46

Joined
Jun 12, 2010
Messages
483
Location
virginia
Please excuse any ignorance on my part, I'm just trying to learn. According to Castrol's website, Castrol 0w-40 Viscosity cST @ 40 degree C is 66 and @ 100c is 12.7. Castrol 5w-40's is 69 and 12.8. Mobil 1 5w-40 cST @ 40 degree is 80 and 13.7 (Mobil 1 website.) Now I found this searching on Google "People also ask"...."Is higher viscosity better?"

The slope of the lubricant with a high VI is more horizontal: the viscosity remains more stable across a wider temperature range. This means a lubricant with a higher viscosity index is more desirable, because it provides a more stable lubricating film over a wider temperature range. Apr 17, 2020

This is in regards to the low pressure light blinking on my 2004 325i @ idle w/ engine warmed up. (Slight increase in revs, light no longer blinks.) This is the question I asked the BMW shop mechanic as to the cause and could it be oil related. (This is when he stated he would not use an "0" weight oil.)

On the next OC (in December), I plan on using the Mobil 1 Euro 5w-40 oil. Will be interesting to see if the oil pressure light continues to blink w/this oil? Will follow w/this info and thank-you once again for this wonderful website and all its member's knowledge and insights. Thank-you.
 
Joined
Mar 8, 2012
Messages
16,262
Location
Colorado Springs
Please excuse any ignorance on my part, I'm just trying to learn. According to Castrol's website, Castrol 0w-40 Viscosity cST @ 40 degree C is 66 and @ 100c is 12.7. Castrol 5w-40's is 69 and 12.8. Mobil 1 5w-40 cST @ 40 degree is 80 and 13.7 (Mobil 1 website.) Now I found this searching on Google "People also ask"...."Is higher viscosity better?"

The slope of the lubricant with a high VI is more horizontal: the viscosity remains more stable across a wider temperature range. This means a lubricant with a higher viscosity index is more desirable, because it provides a more stable lubricating film over a wider temperature range. Apr 17, 2020

This is in regards to the low pressure light blinking on my 2004 325i @ idle w/ engine warmed up. (Slight increase in revs, light no longer blinks.) This is the question I asked the BMW shop mechanic as to the cause and could it be oil related. (This is when he stated he would not use an "0" weight oil.)

On the next OC (in December), I plan on using the Mobil 1 Euro 5w-40 oil. Will be interesting to see if the oil pressure light continues to blink w/this oil? Will follow w/this info and thank-you once again for this wonderful website and all its member's knowledge and insights. Thank-you.
You have mechanical issue!
I track my BMW and before installing oil cooler I would reach 300f oil temperatures! Never had pressure issue and that was using Mobil1 0W40 (KV100 12.9cst). I used Castrol 0W40 (not the one you cited. That on is not on the market yet) on track with excellent results with oil temperatures around 260-270f. No pressure issues.

How is you oil pump? Remember, M54 had issues with oil pump bolts.
 
Joined
Dec 15, 2002
Messages
1,331
Location
Simpsonville SC
I would definately check the oil pressure with a manual gauge before trying to "solve" a flickering light with a change in oil viscosity. Won't happen with oils available within reasonable ranges anyway. Plus, it could be something as simple as a bad pressure sending switch or sensor. Way cheaper than trying to chase the issue by throwing all different types of oil at it.

My bet is your pump has opened up due to age.
 
Joined
Apr 15, 2010
Messages
8,220
Location
Atlanta,GA
My E46 had a flickering oil light and it was due to oil wicking into the harness. Of course it's possible that the nut holding the sprocket for the oil pump is backing off which causes the sprocket spin freely around the shaft.
 
Top