Long Summer Trip Advice for GM 1.5L GDI Turbo: Premium Fuel if running @ GVWR ?

[LoneRanger]

My wife, her mother, and her two sisters will be taking the new GMC out east towards end of July, about a 12 hour drive each way. Car will be close to gross weight. My question is, although the engine is spec'd for regular unleaded 87, would it be a good idea to probably ask her to use 93 premium instead for the entire trip? I'm considering this in light of the conditions which will be expected to be hot and the car loaded near gross weight.

Main consideration is minimization of the ever present possibility of LSPI on these small gasoline direct injection turbo engines. Seems wise to feed it premium for a long heavy haul in the heat. The cruise on the interstate not being the risk factor, but instead the low rpm high boost condition that would arise when, say, departing rest stops, which will be a frequent occurrence given the occupant demographic. Car parked just long enough at the bathroom stop to bloom excess engine heat, then start-up and getting back on the highway may represent an increase in the potential for low rpm high boost. It would be better to leave the car idling (take turns going to pee) so the cooling system can control heat, but that won't be happening.

Over thinking it? Yes. But this is BITOG. It's what we do.

 

[Speak2Mountain]

Amsoil, Redline, or Mobil AP in correct viscosity

 

[LoneRanger]

Originally Posted by Speak2Mountain
Amsoil, Redline, or Mobil AP in correct viscosity


Good choices. I'm aware of the known link between motor oil and LSPI and the car is, and will be, running dexos2 AC Delco OEM synthetic in the proper (per manual) viscosity.

 

[skyactiv]

Reality?
GM knows no one buying something other than a Corvette or Camaro wants to put anything but 87 octane in it. That is why GM is pushing for the new standard octane to be 91 at the gas pump.
For the gas engine to continue being offered down the road, it has to happen.
https://www.forbes.com/sites/samabu...-gas-to-be-the-new-regular/#de1b6326e9d0

Taking turns to pee so you can leave the car running is absurd. If it had a shot battery or starter, I could see it.

 

[ARCOgraphite]

I have a hard time running Premuim in my Jetta 1.4 Tsi turbo. It's been more miss than hit getting fresh good fuel. THE ENGINE RUNS POOR ON STALE PREMIUM.

I would just go with the regular. They are going to be mainly off boost on the high way at a steady speeds.

Ypu are overthinking things. Just drive the pig and see what happens.

On my Lease Jetta I've haven't even changed the factory fill yet at 6 months and 5K miles and the thing runs better than cars i've owned and fretted about. (maybe its BC it has REAL synthetic in it - not the usual North American garbage spec ILSAC junk)

Just let it go. Let it go. Its O.K. It's Just a car.

Not really important in the overall scheme of this silliness we make of this great Universe.

Wisdom from AlleyCat from Subaru.forester.org

 

[c502cid]

Originally Posted by skyactiv
Reality?
GM knows no one buying something other than a Corvette or Camaro wants to put anything but 87 octane in it. That is why GM is pushing for the new standard octane to be 91 at the gas pump.
For the gas engine to continue being offered down the road, it has to happen.
https://www.forbes.com/sites/samabu...-gas-to-be-the-new-regular/#de1b6326e9d0

Taking turns to pee so you can leave the car running is absurd. If it had a shot battery or starter, I could see it.



Gotta love the point in the article saying if 91 becomes the new standard then prices will come down on it from the efficiencies of producing more. hahahahhahaha!

Here in the Rockies they still sell 85 octane as regular. My Trax and my F150 manuals both say do not use lower than 87 (mid grade here) no matter what the altitude. When we first got the Trax (1.4 turbo, not DFI) which is my wife's daily driver I put in 85 for about a year until I finally read that point in the manual. Changed it up to 87 and my wife, who has no clue what fuel is in it, noticed it immediately.

 

[csandste]

"Over thinking it? Yes. But this is BITOG. It's what we do."

Any reports of LSPI in this engine using Dexos 1.2/SN+ and 87 octane? If not, i do think you're over thinking.

 

[gathermewool]

If the manual recommends premium, then run premium. What you don't want, is for your wife to continue to switch between premium and regular throughout the trip, though. If she refuses to use premium or won't remember, then just stick with regular.

Switching:

Just as soon as the ECU learns it can max out timing/fueling to take advantage of the higher octane fuel, it has to rapidly retard all of that to compensate for a step change in octane to regular. I'm sure the ECU is fast enough to prevent damage, but I wouldn't want to be that ECU trying to do all of that while your wife enters an on-ramp and guns it after having switched from 93 to 87!

//

I can imagine that small turbo spooling more often than you'd think. According to my logs, moderate to aggressive tip-in is where I mostly see knock in data-logs.

//

LSPI is not so much a function of the fuel used. The ECU will sense the slightest knock and either change timing (spark/fuel) or add fuel to compensate for normal load-based knock. If it occurs a few times, the ECU will memorize that load and RPM and anticipate that knock event before it happens.

LSPI is random and I'm not sure exactly what causes it. My best guess is that it's PCV components, such as calcium, entrained in the vapor that pre-ignites and results in a different amplitude spike in pressure than the knock your ECU is anticipating. This is likely random or given certain conditions or given a certain level of gunk/carbon buildup in the engine/valves. Premium may mitigate this, but likely won't stop it, if it's going to happen.

 

[LoneRanger]

gathermewool, the linked studies I read in the LSPI threads on here do in fact point to calcium levels in the additive package of motor oil as a possible influence on LSPI. Hence (I think) to pass dexos2 an oil cannot have above 2000 ppm calcium or was it 1800? They use more magnesium to compensate for lower levels of calcium. And boron seems to be present in concentrations of at least 80 ppm or more in most dexos 2 oils.

 

[walterjay]

I would use 89 octane if you are really pushing the car with tough driving conditions. It doesn't cost that much more. I have a 1.6 turbo which runs remarkably better on 89 in warm weather. It does not improve mileage but increases driveability and performance. Probably no need for premium if the car does not spec it.

 

[edyvw]

Originally Posted by c502cid
Originally Posted by skyactiv
Reality?
GM knows no one buying something other than a Corvette or Camaro wants to put anything but 87 octane in it. That is why GM is pushing for the new standard octane to be 91 at the gas pump.
For the gas engine to continue being offered down the road, it has to happen.
https://www.forbes.com/sites/samabu...-gas-to-be-the-new-regular/#de1b6326e9d0

Taking turns to pee so you can leave the car running is absurd. If it had a shot battery or starter, I could see it.



Gotta love the point in the article saying if 91 becomes the new standard then prices will come down on it from the efficiencies of producing more. hahahahhahaha!

Here in the Rockies they still sell 85 octane as regular. My Trax and my F150 manuals both say do not use lower than 87 (mid grade here) no matter what the altitude. When we first got the Trax (1.4 turbo, not DFI) which is my wife's daily driver I put in 85 for about a year until I finally read that point in the manual. Changed it up to 87 and my wife, who has no clue what fuel is in it, noticed it immediately.

I am running 91 in Toyota.
On 85 there is obvious knocking. 87 on regular gas stations is almost as same price as 91 in Costco, so I just run 91 from Costco. There is more than obvious difference, not in power, but a. smoothness of an engine, a b. it seems engine is more enthusiastic in higher rpms. where peak torque is available in this particular engine.

 

[Malo83]

Originally Posted by walterjay
I would use 89 octane if you are really pushing the car with tough driving conditions. It doesn't cost that much more. I have a 1.6 turbo which runs remarkably better on 89 in warm weather. It does not improve mileage but increases driveability and performance. Probably no need for premium if the car does not spec it.


89 would be my choice also with an oil and filter change before the trip.

 

[Rand]

Originally Posted by ARCOgraphite


Wisdom from AlleyCat from Subaru.forester.org


Quoting yourself and calling it wisdom lol

 

[JamesBond]

I wouldn't give her extra things to worry about during her vacation. Just let them enjoy the trip in the nice new car without filling her head with thoughts of the engine blowing up.

If you want to run premium start afterwards.

 

[LubeFiner]

Originally Posted by skyactiv
Reality?

For the gas engine to continue being offered down the road, it has to happen.
https://www.forbes.com/sites/samabu...-gas-to-be-the-new-regular/#de1b6326e9d0


This plan appears to be a new way to charge people more money for vehicles and the fuel to run them. All in the name of profits and to [censored] with the consumer, which is the typical mindset of todays corporations.

 

[Eddie]

I'd use a TOP TIER 87 octane. Ed

 

[gathermewool]

WHAT DOES THE OWNER'S MANUAL SAY IS RECOMMENDED?

Knowing what your OM spec's would greatly help the conversation.

 

[LoneRanger]

Agreed, but believe I mentioned the car is spec'd for 87. By spec'd I meant specified, which means in manual.

I'd appreciate if guys would stop insinuating that I've not perused the manual. I have, but I have done so selectively by keyword searching the PDF version to jump to whatever info I'm looking for.

 

[02SE]

Yes, tell the wife, MIL, and SIL's to take turns peeing...

This is a new car, with a cooling system that I would hope was designed correctly, so the engine temperature should stay in the acceptable range regardless of ambient temp, and a not overloaded vehicle. If it can't handle a nice cruise down the Interstate, with some bathroom breaks, it's time to trade it in.

 

[nthach]

We don't know if GM incorporated a "hotter" fuel/ignition/boost map for higher octane fuel for that 1.5T to really perform. I know the Japanese do say "premium fuel is recommended for best performance, but regular fuel is OK" in their owner's manual. GM did after all, create the dexos oil standards and they approve/certify oil to carry the badge. D1G2 is a response to LSPI and I'm sure the PCM's strategies is to catch LSPI before it happens as well.

It wouldn't hurt to run premium, but I don't think the girls would want to be in charge of datalogging.