Brand: What kind of gas for 1967 Impala?

  • Article by: PAUL BRAND
  • Updated: March 29, 2013 - 1:06 PM

Q: I recently bought a one-owner ’67 Chevy Impala with only 73,000 miles that’s in very good shape. I’ve started a work list for spring that includes checking the antifreeze and transmission fluid and changing the fluids that need changing. The 327 V-8 engine is original and the owner left a note stating to add a lead additive if using a lower octane gasoline, but if non-oxygenated gas is used, no additive is needed. I filled it with non-oxygenated gas the day I picked it up in mid-December. Is it OK to start and run it every few weeks for the rest of winter?

A: First off, congratulations on finding a true “survivor” from the 1960s. Very few of these vintage vehicles are still original, unmolested and unrestored, which to my mind makes them even more appealing.

Let’s clear up some confusion here. Generally speaking, engines built before about 1970 required tetraethyl lead in the gasoline to provide two important requirements. First, lead was an inexpensive octane enhancer to increase the octane level of gasoline for higher compression engines. Second, lead provided a heat-transfer lubricating quality for valves. The lead helped transfer and dissipate heat from valve heads to valve seats to prevent burned valves. From about 1970 on, engines feature hardened valve seats and stellite or sodium-filled exhaust valves to handle more heat, negating the need for lead for this purpose. Today, tetraethyl lead is banned from road use motor fuels due to its toxic nature.

While the engine in your ’67 Impala was built for leaded gasoline, there’s likely more than enough lead buildup in this original engine to protect valve seats — particularly in light-load conditions like winter warm-ups and recreational driving. In fact, I wouldn’t worry about the engine when using today’s unleaded fuels unless you’re going to run the engine particularly hard. The correct choice of gasoline for your vehicle would be premium non-oxygenated to provide adequate octane as well as protect the fuel-system components from degradation due to the alcohol content of ethanol-blended gasoline.

But here’s the information you and the rest of us driving older vehicles need. Non-oxy gasoline is not a substitute for the lubricant quality of leaded gasoline. There are legal fuel additives classified as “metallics” that offer some of the heat-transfer capability of tetraethyl lead that you can use to protect valves and valve seats on older engines.

Since the only permanent “fix” for pre-1970s engines is to remove the cylinder heads to install hardened valve seats and new valves, I’d suggest driving the car until some type of symptom requires disassembling the engine. Upgrade the valves and valve seats at that point.

Q: My son owns a 2006 Mini Cooper. The muffler had a heat shield on it, which has fallen off. The Mini service center stated it was nothing to worry about. As a mother, I do worry about it. Should we be replacing the muffler?

A: On most vehicles, the heat shield on the exhaust system protects the catalytic converter, not the muffler. The reason is simple. Temperatures inside the converter can reach well over 1,000 degrees and the outside shell can reach 200 degrees or more. Mufflers typically don’t get that hot.

The heat shield protects the catalytic converter from coming into physical contact with — and potentially igniting — leaves, newspaper and other combustible materials. If the heat shield begins to rattle due to broken mounts, it can sometimes be reattached or secured by welding or steel straps. Once the shield is completely missing, the only fix is to replace the catalytic converter — a potentially expensive repair.

If the missing heat shield is part of or protects the muffler, I would be less concerned. The repair, which would involve replacing the rear half of the exhaust system, would be less costly.

  • get related content delivered to your inbox

  • manage my email subscriptions

ADVERTISEMENT

New England 2/1/15 5:30 PM
Seattle
Portland 0 Postponed
Brooklyn 0
Sacramento 0 Postponed
New York 0
Philadelphia 74 FINAL
New Orleans 99
Minnesota 84 FINAL
Oklahoma City 92
Orlando 94 FINAL
Memphis 103
Boston 99 FINAL
Utah 90
Denver 98 FINAL
LA Clippers 102
Army 68 FINAL
American Univ 66
Wright State 64 FINAL
Detroit 53
Syracuse 83 FINAL
North Carolina 93
Cleveland State 56 FINAL
Oakland 59
Delaware State 54 FINAL
NC Central 55
High Point 63 FINAL
Presbyterian 54
Howard 45 FINAL
Bethune-Cookman 42
Coppin State 84 FINAL
NC A&T 71
Nicholls 51 FINAL
Northwestern St 80
Hampton 56 FINAL
SC State 65
Gardner-Webb 59 FINAL
Campbell 78
MD-Eastern Shore 72 FINAL
Florida A&M 65
Stephen F Austin 82 FINAL
Lamar 65
Central Arkansas 67 FINAL
New Orleans 87
Norfolk State 70 FINAL
Savannah State 54
TX A&M-CC 70 FINAL
SE Louisiana 61
Sam Houston St 80 FINAL
Abilene Christian 63
McNeese State 84 FINAL
Incarnate Word 86
Milwaukee 48 FINAL
Valparaiso 73
Alcorn State 66 FINAL
Alabama A&M 78
Southern U 59 FINAL
Alabama State 63
Prairie View 68 FINAL
Ark-Pine Bluff 105
Texas 86 FINAL
Iowa State 89
Texas Southern 85 FINAL
Miss Valley St 84
Long Island 85 FINAL
Bryant 88
Central Conn St 51 FINAL
St Francis-NY 49
Fairleigh Dickinson 0 Postponed
Sacred Heart 0
St Francis-PA 87 FINAL
Wagner 74
Delaware State 59 FINAL
NC Central 66
Howard 53 FINAL
Bethune-Cookman 61
Coppin State 49 FINAL
NC A&T 67
Hampton 88 FINAL
SC State 53
Norfolk State 54 FINAL
Savannah State 56
MD-Eastern Shore 54 FINAL
Florida A&M 64
Angelo State 55 FINAL
Abilene Christian 70
Samford 32 FINAL
(25) Chattanooga 49
Prairie View 83 FINAL
Ark-Pine Bluff 66
Alcorn State 58 FINAL
Alabama A&M 55
Southern U 53 FINAL
Alabama State 49
Texas Southern 63 FINAL
Miss Valley St 52
(12) Texas A&M 61 FINAL
(1) South Carolina 79
Robert Morris 68 FINAL
Mount St Marys 44
East Tenn St 72 FINAL
Mercer 70
Wofford 56 FINAL
Furman 58
Morehead St 64 FINAL
Tenn Tech 54
Illinois 57 FINAL
Michigan 70
Quinnipiac 0 Postponed
Manhattan 0
Saint Peters 0 Postponed
Rider 0
(18) Miss State 59 FINAL
Auburn 48
(15) Nebraska 72 FINAL
(20) Iowa 78
Connect with twitterConnect with facebookConnect with Google+Connect with PinterestConnect with PinterestConnect with RssfeedConnect with email newsletters

ADVERTISEMENT

ADVERTISEMENT

ADVERTISEMENT

 
Close