Heading into WinterWeatherConditions in Northern Michigan I would not  
be

the least bit worried about leaving the 5w30 in there as long as you  
are sure that

your OilPressureSensor is in good working order so as to keep you  
properly informed.

I am of the opinion that oil that is overly thick is harder on an  
engine than oil that is

a bit on the thin side as the thick stuff might not be able to get  
into all areas that it

is needed. I have a Subaru engine in my 90Westy now but back in 09  
just before I

did the swap I ran my 2.1H2OBoxr on 5w30 for 3000mi without any issues  
during

the hottest months of the year here in NM & for curiosity &  
PeaceOfMind I had the

OilPressure professionally checked & it was just fine ~ my H2OBoxr did  
have 120K

fewer miles than yours though. I normally ran that engine on 10w40 &  
would never

run anything thicker than that unless I was experiencing low O'P'  
issues.

                                                        ORR ~ DeanB

On 21 Nov , 2012, at 5:51 PM, John Meeks wrote:

> So, I drained my oil last weekend but when I grabbed the jug of 10w40
> Mobile1 off the shelf, to my great dismay,  found a jug of old used  
> oil.
>
> With no vehicle to get new oil I borrowed some 5w30 synthetic and  
> have been
> nervously driving with it for a week.
>
> The engine is a 2.1 with 250k miles on the odo. Even fully warm, no  
> flicker
> of the oil light at idle.
>
> Can I just drain a couple of quarts and add 15w50 synthetic ?
>
> Van is in Northern Michigan where it gets below 0�F maybe 10 days a  
> year
> but mostly 20's. Driven about 150 miles a week.
>
> I'd rather not spin a rod bearing so any advice is fully appreciated.
>
> John Meeks
> '91 Multivan Phoenix
> http://www.vanagonauts.com
> Vanagon Rescue Squad
> with iPhone and Android apps