5W 20 vs 5W 30 oil

moderat0r · 04-05-2026, 10:44 AM

hello,
I bought 5w 20 full synthetic by mistake instead of 5w 30 full synthetic , I cant return it anymore

Brand/product name - Pennzoil Platinum Synthetic 5W20 Motor Oil 5L

Car is being run on 5W 30 full synthetic for few years

can I use 5w20 for one year or so?

is that going to affect anything ?

I am in Detroit/Michigan region weather zone

N52 engine PG77
124K miles on odometer
323 E90
year 2011

Thankyou

lookalikehuuh · 04-13-2026, 02:58 PM

I would not put 5w20 in a car that wasn't designed to run it.

A car designed to run on 5w30 has larger tolerences in important engine parts like rod, bearing, main bearings, etc. If you use a thinner oil, its very likely you won't produce enough oil pressure to properly lubricate the engine and may experience engine failure. Espeically with the wear that would be associated with 120K+ miles.

Don't let $30 worth of oil compromise your entire engine.

04-05-2026, 10:44 AM	#1
moderat0r Private First Class 20 Rep 128 Posts Drives: BMW e90 323i sedan Join Date: Mar 2019 Location: Canada iTrader: (0)	5W 20 vs 5W 30 oil hello, I bought 5w 20 full synthetic by mistake instead of 5w 30 full synthetic , I cant return it anymore Brand/product name - Pennzoil Platinum Synthetic 5W20 Motor Oil 5L Car is being run on 5W 30 full synthetic for few years can I use 5w20 for one year or so? is that going to affect anything ? I am in Detroit/Michigan region weather zone N52 engine PG77 124K miles on odometer 323 E90 year 2011 Thankyou __________________ \| Model 323i U1 \| Year 2011 SEDAN \| Development Code E90 (MUE) \| Type PG77 \| Miles 95000
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04-13-2026, 02:58 PM	#2
lookalikehuuh Colonel 1884 Rep 2,177 Posts Drives: 2006 330i, 2007 335i Join Date: Sep 2014 Location: San Diego, CA iTrader: (0)	I would not put 5w20 in a car that wasn't designed to run it. A car designed to run on 5w30 has larger tolerences in important engine parts like rod, bearing, main bearings, etc. If you use a thinner oil, its very likely you won't produce enough oil pressure to properly lubricate the engine and may experience engine failure. Espeically with the wear that would be associated with 120K+ miles. Don't let $30 worth of oil compromise your entire engine.
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