Best 15w40 for very long term storage

I have a generator now, and I want to put a gallon or maybe two of 15w-40 in storage for it. If I am ever in a power outage a gallon will get me about 8 days of constant use run time - 16 oz per change / 24 hour intervals.

If I am lucky I may never need to use this - so I am looking for an oil that will keep best for years and years. I know technically most places rate 6 year storage, and likely they will last much longer than that. I will store this in a non temperature controlled windowless shed, and the most likely use case will be to run this thing while very hot and humid - south Carolina coast.

Some potential candidates I can get locally - although I could order about anything:

Shell T1 SAE 30 - cSt 100 @ 11.9 - I threw this one in as technically the spec is to use SAE30​
Shell T4 15w40 - cSt 100 @ 15​
Delvac Extreme 15w40 cSt 100 @ 14.3 -- full synthetic​
Delvac 1300 super 15w40 I think this one is cSt 100 @ 14.8, but the literature on this particular formulation confuses me. This one is cheapest - $13 bucks on walmart.com​

Or whatever else is out there. Leaning towards the Delvac Extreme because it full synthetic.

Anyone care to weigh in?

I don't think it matters - keep it sealed and in 10 years the oil will still be oil. Even if some of the additives degrade some it will still be GTG for your generator.

But some of the 4-5 quart jugs of oil have a foil seal under the cap - and some don't -

It seems like a solid seal with no air leaks would be better - also gives you tamper resistant seal.

The Supertec, Chevron and Mobil1 have this for sure, not sure about the others.

You could do what I did - find something that looks good that is on sale or clearance. You have time on your side - or

Grab 2 of these - $28.64 for 2 gallons - so $57.28 for 16 quarts - $3.58 a quart --- Free shipping over $35




Or buy one 2 gallon jug of 15w40 Supertec and buy one quart of Valvoline 10W40 for $6.37




$28.64 + 6.37 = $35.01 = free shipping and 9 quarts of oil for $3.89 a quart!!!

Or one 2 gallon jug of 5W40 and one 1 gallon jug!
 
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I personally wouldn’t store a generator long term. If you plan on relying on it, it should be excised regularly. Every 3-6 months under load perhaps.

I would be more worried about an E0 fuel. As far as oil, I’d run a 0w40 and be done with it. Depending on your climate, a 15w40 will work too.

I wouldn’t be too worried about having a “generator only” stash either. In a pinch, any xw30 will work assuming you already have some for a car, mower etc.
I have been running it monthly. I use ethanol free gas because I have it here anyways, and I run the carb dry then drain the gas. I think I will be going to every couple months as this seems a bit much - but its what the manual said and it really doesnt' take as long as it sounds - like I said I am all set up for it.
 
I have been running it monthly. I use ethanol free gas because I have it here anyways, and I run the carb dry then drain the gas. I think I will be going to every couple months as this seems a bit much - but its what the manual said and it really doesnt' take as long as it sounds - like I said I am all set up for it.

If you drain the carb and also the fuel tank you can store it for months (years even) without any issue.

I bought a Wen Power Pro 3500 in 2004, ran it a few hours during a hurricane - changed the oil - drained the gas out of the carb and also out of the fuel tank - bone dry. Then put it back in its box where it sat unused until 2016.

A storm was out in the gulf so I pulled it out of the box a few days before it was going to hit just to see what I had - filled it with gas and it started on the first pull. Ran it for about 20 hours while power was out and changed the oil, drained all the gas and put it back in its box. I got a new Honda so no need to run it since - so it is my back up.

BTW you should check the fuel lines on an older generator they get hard and brittle. I paid Wen $12 for a fuel line - it is about 7 inches long - I then ordered 3 meters of fuel line from eBay for $2.50. No auto parts store had the correct size. Wen shipped it and I got it 2 days later - the stuff I ordered from eBay took 2 months.

The reason you start them every month is to make sure the carb doesn't plug up if you don't drain the fuel -

But of course not a bad idea to pull it out every few years to make sure it works -
 
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