Syn oil in generator

427435

If you think 10W synthetic is the same as 10W dino try this: compare viscosity of dino oil when cold and when draining hot from the engine-runs like water. Then try the same with synthetic oil of same rating. Synthetic oil has very high viscosity index and viscosity changes little with temperature, dino does not, mostly due to wax content.

I use synthetic oil in everything that has the engine including pressure washer and lawn mover since 1974. Since 1976 I use only 5W-30 Mobil I in all my engines and the last oil leak I had was on 1984 Jeep Cherokee with 1983 Chevy 2.8l engine that had length of rope (too short) for crankshaft seal. No leaks in motorhome, pick-up, Jeep, car, boat, both generators, pressure washer or lawn mover.

I use synthetic oil in everything I own. Mobil 1 5W-30W (the bottle with the gold cap for extended performance) RV, CRV, Harley, Cub Cadet riding lawn mower and to lube my pellet stove. Been using Mobil 1 since the early 1980's.

Bruce Brown wrote:

427435 wrote:

dougrainer wrote:
35 years ago when Mobil 1 first came out, we had a Mobil engineer that purchased a Motorhome from us. I asked about the NEW at that time syn oil. He stated that you never install Synthetic oil in a engine that has already been broken in. He said that the Synthetic oil will leak thru extremely small cracks and voids in seals that normal oil would not. He laughed and said, install it and you will then have leaks you never knew you had. Doug

BS. I've switched a lot of used engines to Mobil 1 over the years without ever having a problem. That includes a couple of IH Scouts with over 70,000 miles at the time I bought them, a used riding lawn mower, a 1993 Ford Thunderbird, a 1991 Ford PU, my used MH (32,000 miles) and its genset. Never had an issue with any of them.


A 10w oil is a 10w oil whether synthetic or dino.

I'm not going to 100% agree with you on that.

Part of my daily employment is selling lubricants. We are currently working on a full mill change over to the brand we sell.

The issue of synthetics came up, and our factory lubrication engineer flatly said, sometimes synthetics cause seals to shrink and create leaks. Not always, sometimes, and the older the piece the better the chance of leaks.

So yeah, it can happen.

Having said that, I've switched things over myself and never had an issue. In the OPs case it was an older unit and switching back cured it - I'm thinking we know why. :W

Is the factory lub engineer a factory employee or an employee of the lub company? If he is a factory employee, he is badly out of date on synthetic lubes. If he's the lub company engineer, I would find another lube company.

That "theory" goes back 40+ years to the very first synthetic lubes that had problems. As another posted, that was quickly correctly, but things live on and on--------especially on the internet.

Mobil makes a synthetic specifically formulated for high mileage engines. I haven't heard of a synthetic causing seals to shrink since the early days in the 70's before synthetic producers learned to blend better additive formulas, but a switch to current synthetics has been known to clean the crud out that may have been masking an already leaking seal. If a given oil meets the API and SAE specs for that weight oil, then it should work fine in a healthy engine that calls for that spec oil.

427435 wrote:

dougrainer wrote:
35 years ago when Mobil 1 first came out, we had a Mobil engineer that purchased a Motorhome from us. I asked about the NEW at that time syn oil. He stated that you never install Synthetic oil in a engine that has already been broken in. He said that the Synthetic oil will leak thru extremely small cracks and voids in seals that normal oil would not. He laughed and said, install it and you will then have leaks you never knew you had. Doug

BS. I've switched a lot of used engines to Mobil 1 over the years without ever having a problem. That includes a couple of IH Scouts with over 70,000 miles at the time I bought them, a used riding lawn mower, a 1993 Ford Thunderbird, a 1991 Ford PU, my used MH (32,000 miles) and its genset. Never had an issue with any of them.


A 10w oil is a 10w oil whether synthetic or dino.

I'm not going to 100% agree with you on that.

Part of my daily employment is selling lubricants. We are currently working on a full mill change over to the brand we sell.

The issue of synthetics came up, and our factory lubrication engineer flatly said, sometimes synthetics cause seals to shrink and create leaks. Not always, sometimes, and the older the piece the better the chance of leaks.

So yeah, it can happen.

Having said that, I've switched things over myself and never had an issue. In the OPs case it was an older unit and switching back cured it - I'm thinking we know why. :W

Genset was not overfilled and yes it has oil in it. It has been leaking for 4 years and I check it all the time. I posted this to possibly help others with the same problem. I switched to syn 10-30 in the MH at about 50k miles, the tow car at about 70k miles. I figured I would just buy one oil for all three engines including the genset. The MH now has 107k miles on it and never leaked. The tow car 2002 Toyota Corolla leaked right away at the pan gasket. I tightened the pan bolts 3 times before I got the leak to stop. The genset leak did not show up until a year after I switched to syn because it gets used minimally. I could never find the leak and was not about to pull it out and spend another $1000 to fix it as Mr Wizard said. I am just happy it was an easy fix.

I use syn ONLY in my 2014 Chevy Cruze. Some kind of special additive for the turbo. "DEXOS" they call it. Everything else, (pickup, motorhome, motorcycle) get fossil. Never had an oil related problem and don't expect to. Regular changes is the simple and only answer.

Oh, and the (Generac) generator? 10-30 (fossil), Change the oil and filter once a year. No problems. Never had to add any, even with using the generator during "Sandy" for the 72 hours our house power went off.(That...was an extension cord nightmare..but it worked!)

dougrainer wrote:
35 years ago when Mobil 1 first came out, we had a Mobil engineer that purchased a Motorhome from us. I asked about the NEW at that time syn oil. He stated that you never install Synthetic oil in a engine that has already been broken in. He said that the Synthetic oil will leak thru extremely small cracks and voids in seals that normal oil would not. He laughed and said, install it and you will then have leaks you never knew you had. Doug

BS. I've switched a lot of used engines to Mobil 1 over the years without ever having a problem. That includes a couple of IH Scouts with over 70,000 miles at the time I bought them, a used riding lawn mower, a 1993 Ford Thunderbird, a 1991 Ford PU, my used MH (32,000 miles) and its genset. Never had an issue with any of them.


A 10w oil is a 10w oil whether synthetic or dino.

Sully2 wrote:
Ive got 5W-40 Shell in my genset

Me too, with no leaks...

I run synthetic even in lawnmower as I don't want to keep too many oils in my garage.
All my vehicles of last 15+ years run on synthetic, with only exception being Detroit that calls for low-ash oil and only last wife car was factory filled with synthetic.
I always observe lower oil consumption after switching, although buying used vehicles with several leaks it take me some time to fix them all and the observation might not be consistent.
Just a month ago I switched to synthetic motor oil and synthetic ATF on my 2007 Superduty.
The engine had some sweating under, but after the service I noted regural drips that would leave 3" dots on the driveway.
Spend some time under the truck washing and chatting on Ford forum to narrow the leak to main seal. Could not figure out ATF or motor oil as leak was too small to notice level drop.
Drove like that for couple of weeks and ... the leak stop.
Not even sweating I had for last few years.
I am skeptic about engine self-healing, but for now I am happy camper.
Hope you will be too.