Cross-posted (with a few last minute corrections that did not find their way back here) at THE CORNER.
Theme: Solve This Puzzle. Each theme answer is a 3-word, common, in-the-language phrase beginning with the letters S, T, and P, in that order.
16. Makes an offer more desirable : SWEETENS THE POT. Adds some inducements or incentives to an offer you can otherwise refuse.
27. Hopelessly ruined : SHOT TO PIECES. Literally destroyed by firearms, figuratively in a bad state for any reason.
36. Stock trader's goal : SHORT TERM PROFIT. The average holding period of stocks purchased on the NYSE is about 20 seconds. I am not making this up.
44. "Satisfaction guaranteed" catchphrase : SURE TO PLEASE. Ad slogan.
58. Editor's "Whoa!" : STOP THE PRESSES. Wait a minute, something just came up . . .
And the unifier:
58. Auto additives co. that hints at this puzzle's theme : STP. A company that makes engine oil and fuel additives, functional fluids and appearance products for your car or truck, and sponsors racers.
Hi gang, it's JazzBumpa, fresh from rehearsal and finishing off a busy day with an outing with our good friends C.C. and Don. Hop aboard and let's see where they take us.
1. Religious ritual : MASS. Not just any RITE (my first shot) but the Catholic service.
5. Bell sound : PEAL. Ding-dong, not this appealing belle.
9. Like freshly washed hair : DAMP. Or today's weather in S-E Michigan.
13. Skip : OMIT. My peer group demonstrates what can happen if you OMIT your partner.
14. Used cars : RODE. Nice misdirection - not pre-owned vehicles, but motor trips you have taken.
15. Jacob's twin : ESAU. He was the hungry one who gave up his birthright for a not particularly appetizing meal.
19. Entertain at one's loft : HAVE UP. Or, perhaps, invite someone up to your 6th floor walk-up.
20. Big rig : SEMI. Trucking. The tractor part of a tractor-trailer rig.
21. Lookers : EYERS. Lookers use their eyes, for sure; but "lookers" can also mean "those worth looking at." Here is a cross-section.
22. Org. that provides handicaps : U.S.G.A. U. S. Golf Association. A handicap is a numerical representation of a player's ability. A low number indicates higher ability.
24. They appear before U : R-S-T. Clever clue for an alphabet string.
31. Digital comm. method? : A.S.L. American Sign Language - a nice misdirection - here, digital means "of the fingers," rather than something expressed in discrete numerical form.
34. Santa __ winds : ANA. Strong, hot winds from inland towards the sea. Perhaps our California contingent can elaborate.
35. Dumbbell : STUPE. Someone who's not very bright, possibly even stupid.
41. Former country on its own peninsula : KOREA. I guess it's a former country because it has been severed into two separate current countries.
42. Little piggy, so to speak : TOE. Remember the "low digits" clue from not too long ago?
43. Govt. Rx watchdog : F.D.A. Food and Drug Administration
49. Ranch handle : TEX. Typical nickname for a cowpoke.
50. Votes of support : AYES. I agree.
51. Editor's ruthless overhaul, informally : AX JOB. Not an expression I'm familiar with, though the meaning is clear. "Hatchet job" seems more natural.
55. Blog comment : POST
57. Take to the air : AVIATE. It's plane to see, you can entertain at a much higher elevation than a mere loft.
62. Shock with a stun gun : TASE. "Don't tase me, bro!"
63. Cookie since 1912 : OREO. A cream filled sandwich cookie, in black and white.
64. Ripped : TORE
65. Multicolored : PIED
66. Geeky type : NERD
67. Foul mood : SNIT
1. Mideast statesman Dayan : MOSHE
2. Network marketing giant : AMWAY. Founded by Richard DeVos and Jay Van Andel in Ada, MI.
3. Strainer : SIEVE. Kitchen gadget.
4. Takes the helm : STEERS.
5. SAT practice : PREP. SAT used to stand for something - Scholastic Aptitude or Scholastic Assessment Test. Now it's just a three letter name (like STP) for a standardized test used in college admissions. To PREP is to prepare, which sort of blows the purpose of the test.
6. Long time, even in the singular : EON. Still, two EONS are longer than one.
7. Paper back items? : ADS. More misdirection from the devious duo - not a paper-back book, but the back section of your news paper.
8. "Time to leave" : LET'S GO. ¡Vámonos!" en Español.
9. Regard : DEEM
10. Aim for : ASPIRE TO. To ASPIRE is to aim high, from the Latin word for desire.
11. Statesman on a 100-yuan note : MAO. Chairman MAO Tse-Tung, former leader of the Chinese Communist Party and author of "The Little Red Book.
12. Delay, with "off" : PUT. Never do today what you can PUT off until tomorrow.
17. Fanny : TUSH. Human hindquarters. Does anyone have background on this word?
18. Clunker : HEAP. Either way, a decrepit automobile, possibly in need of STP.
22. __ Reader: eclectic bimonthly : UTNE. Magazine founded by Eric UTNE and Nina Rothschild UTNE.
23. Surprise with a "Boo!" : STARTLE. I stopped when she startled me, and didn't restart because I was estopped.
25. Shoe mark : SCUFF. A mark on the shoe, not a mark made by the shoe. I almost missed the mark.
26. Lukewarm : TEPID
28. Brittle cake grain : OAT
29. 1-Down's land: Abbr. : ISR. Israel. MOSHE Dayan was an Israeli military leader and politician.
30. Words with date or record : SET A. To SET A record you have to break a record. To SET A date, breaking a date is not usually required
31. Seeks, as permission : ASKS. Could I? Pretty please with sugar . . .
32. Loud tone : SHOUT. Tone of voice. I was thinking of a musical tone.
33. Moto player : LORRE. Peter Lorre portrayed Kentaro Moto, a Japanese detective, in a series of eight movies from 1937 to '39, based on the novels of John P. Marquand.
37. Uncover again : REEXPOSE. Imagine something being uncovered, recovered, then REEXPOSED. The imagery is quite amusing
38. What Tweety tawt he taw : TAT. Tweety is the famous EYER of a certain fat cat.
39. "The Simpsons" bar : MOES. Everything I know about the Simpsons I learned from crossword puzzles.
40. Green shade : PEA. From the eponymous legume.
45. Brewery oven : OAST. This is a kiln for drying hops.
46. Long boa : PYTHON. A snake, not a long, fluffy scarf.
47. Keep for later : SAVE
48. Lives : EXISTS. A singular verb, not a plural noun.
52. "Friday the 13th" villain : JASON. Jason is the slasher in an even dozen horror films. Why is there no Friday the 13th 13?
53. Ferrell's partner in "SNL" Spartan Cheerleaders bits : OTERI. Cheri OTERI and Will Ferrell, as Craig and Arianna, cheered for their High School chess team.
54. Harass : BESET. Cheri OTERI and Will Ferrell, as Craig and Arianna, BESET their H.S. chess team
56. Guest columnist's piece : OP-ED. A feature or commentary printed on the page OPposite the EDitorial page.
57. 2007 signer of the richest contract in MLB history : AROD, aka Major League Baseball player Alexander Emmanuel (Alex) Rodriguez of the New York Yankees. Of course, we will have baseball!
59. Mai __ : TAI. The rum concoction so familiar to cruciverbalists.
60. Long beginning? : ERE. Beginning signifies a prefix fragment. ERElong is an archaic way of saying "before long."
61. By authority of : PER.
There you have it folks. Hopw you enjoyed the ride. Constructor's notes follow ERElong, PER C.C.
Don came up with STP when we were brainstorming a common acronym expanding idea. Rather than going with THE for all the middle words, we tried our best to come up with different S* T* P* phrases. The long theme entries (13x2, 14x2 & 15) made the gridding challenging. Don tried various grids and finally decided to go with Rich's corner blacks suggestion (the three black squares along the top right and lower left edges of the grid). Don call them side pockets. Hope it's a smooth solve for you. A big Thank-you to eddyB for the quick and detailed STP answer in our early brainstorming session.