Thicker oil in the summer -- a good idea?

[Brit33]

Spyder is a very different engine design.
The 8v flat four boxers with flat tappets in buckets require min 50 viscosity.
many owners in Europe I know run their engines very well with Castrol 10w60 or Motul 15w50.
I think the 16v injection models can get away with a 10w40 oil, (these have spray jets to keep the pistons cooler).
My S2 33 has no spray jets, the sump is right next to the exhaust manifolds also.
Mine is recently rebuilt also so no big end issues.
They rev high though and can have a high fuel dilution due to the double twin carbs.

Originally Posted By: Quest
Originally Posted By: Brit33
wow it surprises me how thin the oil you guys are using with these modern cars.
Our old boxer alfas from Europe specify a min of 10w/50.
In hot 35-40c summers my tappets tend to bleed down with a 50 oil.
10w/60 is working just nicely.


Given the VII content to get a 10W60, I suspect that there's pretty significant shearing issue going on.

Last time I serviced an Alfa spyder converable (2-dr, FI), I used 10W30 for 6kkms.

Q.

 

[CATERHAM]

Originally Posted By: fdcg27

If your Fit had a temp/visc chart in it's OM, it would no doubt recommend a thirty or even a forty grade for really hot weather.
The OM doesn't have such a chart, because Honda determined that the engine would survive just fine if a twenty grade were used under all conditions.
If it will make you feel better, use a thirty grade for the summer.
It certainly won't hurt anything, but I doubt that the speced twenty grade is causing any measurable harm either.

The old dino viscosity/ambient temp' charts had more to do with what was acceptable in terms of a suitable start-up viscosity and extreme usage at the other extreme.
Ambient temperature by itself is not extreme usage and will not result in high oil temp's just by being stuck in traffic on a 100+F day. Consiquently one need not be concerned in the slightest with running the spec' 20wt oil; it's a none issue.

 

[fdcg27]

Not so sure about that.
Once the thermostat is fully open and the aux fans are running, there can only be higher oil temperatures as a result of higher ambient temperatures.
Whether those oil temperatures get much above 220F or so is another matter.
In most cases, they probably don't.
Still, the old temp/visc charts were not dino charts.
They applied to whatever oil was used.
Where any modern car has a temp/visc chart in the OM (our '09 Forester does), thicker grades are recommended for higher temperatures and severe use, although Subaru also writes that an API SM fuel conserving 5w30 is suitable for all conditions.
Not sure which I should really believe, but I've used a thirty grade in the car for all of the changes I've done from new, save the second 3K, which I ran on Quaker State Conventional 10w40, since I only intended a 3K run, I had the oil, and it conformed with Subaru's requirements for the temperatures encountered during the time I ran it.
I have an idea that the reduced start-up wear from the use of a thinner oil might more than offset any higher wear under very hot or high load conditions.
Don't really know, but viscosity must matter at both ends of the temperature scale.

 

[TFB1]

Originally Posted By: fdcg27
There was a time when every vehicle had a temp/visc chart in its OM.


Yeah back before CAFE...

Other countries still have the same viscosity/temp charts we had 20 years ago for their vehicles that are more or less using same engines we have...

Ought to tell us something but, most can't see the forest for the trees...

 

[Garak]

Originally Posted By: fdcg27
Not so sure about that.
Once the thermostat is fully open and the aux fans are running, there can only be higher oil temperatures as a result of higher ambient temperatures.


It also depends upon how it's driven. Take two identical cars under identical weather conditions with the same oil. Put one car on the track or wide open on the highway and the other on a gentle, 55 mph highway cruise. The former will likely experience significantly higher oil temperatures.

I think CATERHAM's point is that the thicker oil isn't recommended simply because of higher ambient temperatures, but to provide extra leeway for hard driving under those higher ambient temperatures.

 

[fdcg27]

I agree with you.
The thing is that stuck in traffic with the AC running results in higher oil temperatures than does cruising the highway at 55 mph or 85 mph at the same ambient temperature.
Also, most of us would like the oil used to allow for hard driving, rather than being potentially constrained by too low a viscosity, especially since most cars lack oil pressure gauges, and in those that have them, they will usually indicate "normal" over a wide range of actual oil pressures.
I am aware that the spec oil in most cars is adequate for most extreme temperatures likely to be encountered.
I also think that a higher viscosity oil gives an extra reserve for those extremes with no real downside.

 

[Brit33]

Originally Posted By: fdcg27
I agree with you.
The thing is that stuck in traffic with the AC running results in higher oil temperatures than does cruising the highway at 55 mph or 85 mph at the same ambient temperature.
Also, most of us would like the oil used to allow for hard driving, rather than being potentially constrained by too low a viscosity, especially since most cars lack oil pressure gauges, and in those that have them, they will usually indicate "normal" over a wide range of actual oil pressures.
I am aware that the spec oil in most cars is adequate for most extreme temperatures likely to be encountered.
I also think that a higher viscosity oil gives an extra reserve for those extremes with no real downside.


Exactly. As my min. factory specs state a 10w50 I use a 10w60 right now. The engines is 25 years old and is pushed hard in the city. The engine runs quieter with this and I haven't seen any difference in fuel consumption or performance. Just a better oil pressure when hot and quieter lifters.

 

[Garak]

Originally Posted By: fdcg27
The thing is that stuck in traffic with the AC running results in higher oil temperatures than does cruising the highway at 55 mph or 85 mph at the same ambient temperature.


I certainly agree with that, too, and that's been my experience. The old Audi's oil would warm up a bit if doing a huge amount of stop and go traffic in the summer or hanging out in traffic for an extended period. Steady highway speeds were much cooler, and it took a very sustained, high boost run to get it high.

And you're quite right; those cars with oil pressure gauges do have a wide normal range, and worse, don't have terribly useful gradations.