Most cars use hydraulic valve lifters that rely on oil pressure to maintain a tight clearance between the camshaft and rocker arm. If the pressure isnt right, there is play between the lifters and the rest of the valvetrain, which causes a noticeable tap. Its possible that cold oil at startup may help pump up the lifters, but at normal temperatures the viscosity drops, and may be too thin to correctly work the lifters. As the oil breaks down after a few thousand miles it thickens, which eliminates the noise.
1 Heroin is a highly addictive and rapidly acting opiate (a drug that is derived from opium). 2  Specifically, heroin is produced from morphine, which is a principal component of opium. 3  Opium is a naturally occurring substance that is extracted from the seedpod of the opium poppy. (Generally, the purer the heroin the whiter the color, because variations in color result from the presence of impurities.) In the western United States, most of the heroin available is a solid substance that is black in color. 2  This type of heroin, known as black tar, may be sticky (like tar) or hard to the touch.
Heroin is made in several different ways but they all come back to a single base substance which is morphine.Morphine comes from Opium, the resinous substance found inside the fruit of the opium poppy.orphine and codeine are the only two alkaloids which can be converted into heroin. Thebaine is the base for bupenephrine which is a very strong narcotic pharmacologically and is mostly used in the treatment of opiate/opiod addiction.